You shouldn't need a JR pass for either itinerary. You can reach Takayama by train, via Nagoya, but it's nicer to head from Tokyo to Matsumoto, visit the castle, and then take a bus across the mountains. Shirakawago is all buses. It's too touristy for me. Koyasan is best reached on non-JR trains.

I like Koyasan and Kanazawa a lot. I like Takayama and Shirakawago less. That's just me.

You're missing most of the country obviously. Kobe is very close to Osaka should you want to visit. It's linked to Kansai airport by bus, train, and boat.

You need at least a couple of days in kanazawa and at least one full day in Koyasan. My opinion. Tokyo and Kyoto and Nara have a ton to see.

Who knows about golden week. Your biggest problem will probably be accommodation. You'll be in Kansai by then, so you'll only need local transport, which will be fine.

Let me repeat,

you almost certainly don't need any JR pass.

LOL...

I have to admit the posters choice of areas to go and amount of time they want to go to the areas very poorly planned and not very coherent.

Texas is not a worthwhile destination, even with a free plane ticket for the entire family...

You want to spend only 1 night from LA to SF? This coast is one for the prettiest most lovely areas of the USA, and you are rushing through it. I would not take a camper, just a rental cal/SUV oneway, and drop in SF, maybe after a day trip to wine country? You dont want or need a car/camper in SF the city.

You fail to mention any priority in National Parks, or focus on whats of most interest, so you need to read up and do some homework.

You cant take a rental vehicle across border to MX, and any border town in MX is best avoided, major safety issues, drug traffickers and human traffickers.

The mountains and YSNP in late Sept or early Oct would be very cold and snowy, the park is all but closed up. Mountain areas and higher elevations, in the entire western USA, is starting winter, meaning snow.

Late Sept/early Oct in the Midwest, South, and Northeast is prime time.

Have you looked at the Smokey Mountian National Park in Tennessee/North Carolina, very much geared to families to.
You could fly to Wash DC, enjoy all the free Smithsonian Museums, and history, then head to the Smokeys, then to Charleston SC, up to Colonial Williamsburg, and back to DC. Fall colors and weather will ideal. This would be far prettier and enjoyable to anything you have suggested in Texas or MX border, period.

The other area to consider is NYC, a great city, and fun for a family. Train from DC to NY, then train from NY to Boston, then drive a loop up here via lighthouse tours and the coastal and mountain regions, fall colors will be excellent.

So if you focus on California, the southwest parks, the Smokeys/DC area, and the NE NY/Boston and New England states, that would be a great trip full of post card landscapes, varying regional culture, history and food scenes...

Now need to decide on which hotel! I only like city centre hotels.

This is generally not a hotel review forum ... but it seems to me you could be looking at a 2-3 bed apartment on both Airbnb and booking.com.

I don't know Valencia, but in Barcelona it's hard to define a "city centre" - anywhere on the Metro rail service within say 1-4 stations of Passeig de Gràcia would be fine.

The two attractions we enjoyed the most in Barcelona were (1) a day-trip up to the Montserrat mountain monastery, and (2) the Sagrada Familia cathedral ... both were outstanding, but not necessarily great for young children. The main city beach - Barceloneta - was pretty good too, but I guess rather cool in February.

There is a pickpocket issue in busy tourist places - La Rambla and so on - need to watch your personal belongings, but just being sensible is sufficient. No phones / wallets / passports in back pockets or loose backpacks ... unbelievably, people do do such things.

You can't use a village/town as hub in Uttarakhand. For one thing, mountain roads are very slow so any bus travel takes a long time.
But your original post was about an itinerant trek ? There were very long pilgrimage trails in Uttarakhand, but roads have been built on most of them, so Indian pilgrims (excpet for a few saddhus) now go by car/bus to roadheads and only hike the remaining piece of trails in higher altitude to reach the temples / sources of the Gange (there are many of them).

In the past, you could trek by yourself in the Darjeeliong area. But the agencies/guides lobbying has put a end to that, although guides were clearly not necessary. So I don't recommend that area. Also Darjeeling has been affected for years by political and social troubles (strikes).

Domestic tourism is huge in China, so don't expect there to be few tourists.

All these places are good, but between HK and Shanghai, maybe this route (mainly by high speed train):
Hong Kong - Shenzhen North - high speed train to Zhangzhou, then Nanjing (Fujian) to:
(1) Tulous - you won't be able to photo anything like this anywhere else; one night (but you will spend half a day or so getting here). This is the main place where language might be an issue.
(2) Xiamen and Gulangyu island (another night), and not far from the first place - same high speed train route; more interesting photo opportunities
(3) Huangshan, Xidi and Hongcun (another high speed train from Xiamen to Huangshan) - the mountain is pretty scenic, and does attract a lot of people, but it is a big mountain so the crowds can be left behind to some extent. Perhaps worth a night near the summit in an over-priced hotel. Near the base of the mountain are the two 'villages' of Xidi and Hongcun. Both are quite touristy, but nice places to visit and stay a night (or two). Lots of photo opportunities.
(4) On to Suzhou - see some of the gardens; combine with a water town (Xitang or Tongli or there are others; stay a night in one) - depending which place you go, you might need to change the order of places you go.

Finally Shanghai. That would be my route.

If you are interested in exploring great language schools in interesting areas, go off the beaten trail to the mountains of Michoacan and enjoy the beauty of Lake Patzcuaro. CELEP in Patzcuaro is an excellent choice, with small classes, superior teachers and a convenient, central location.

Boy, where to begin...

If you want to go to Bolzano, by all means go. But it seems odd that the very first shout-out to a favorite 2-day stop is precisely the one you were already thinking of. Northern Italy is overly rich in these sorts of destinations, many of which require less of a detour or none at all--Padova, Vicenza, Verona, Mantova, Trieste, Milan, the lakes around Milan, the Tuscan hill town of your choice.

Of course, none of these are in the Dolemites. But are there mountain stops besides Bolzano that are closer and equally rewarding?

If the best thing about Bologna is its usefulness as a base to get to other places... that's not exactly high praise. Especially when there are cheap buses and trains between Ravenna and Faenza that take 35-45 minutes. So I would be in the "Ravenna for 2 nights" camp. After maybe checking your luggage at the Bologna train station and strolling the city center for as long as you find it interesting. There's simply not a lot to do there except eat and stroll the city center. Which is lovely. More lovely than Verona, Mantova, Ravenna, etc? Probably depends who you ask.

Btw, I don't think you could cram Ravenna and Rimini into one day.
(Any informed opinions about Parma/Modena in one day?)

I'm a big fan of Ostia Antica, but I think that's simply a day trip from Rome--not a convenient stop on the way to the airport. You can double-check and see if they'll check your luggage for you. But I doubt it.

I also wonder what you'd miss in Rome if you prioritize Ostia Antica.

Thank you so much for your detailed response, Gsarwa. I need to book our train, so not sure which station yet, but have heard the traffic in Jakarta is very heavy, and we should stay near the station to get an early train. Thank you for the bread tip!

I'm not sure how long to stay in Yogyakarta for as we've not got all the details yet, but 5 days seems about right. I'll start by making a list of all the things to see and do.

That's interesting to rent a car in Ubud. I haven't thought about us driving at all there. We might look into riding a scooter, but I'm a bit nervous, although my boyfriend used to ride a scooter when we lived in Japan. Maybe I'll find is 2-3 places to stay across the island.

Terasi seems to be in a lot of foods. When people have suggested nasi goreng and ketoprak from warung, I'm nervous they will have terasi on them. Is it in most dishes?

The mountain tour you recommend is by car, right? I'll look into it, thank you! :-)

Is a car going to allow me to visit outer sections around Ushguli or is there no reason to have one? I am a biker and traveling with a fold up bike. Looking for the most stunning mountain scenery but not sure about the car? Also, in regards to getting to Abkhazia is it easy to the MFA as well as the border crossing from the train station? I may elect to stay in Mestia or Ushguli instead since I only have 4-5 days. Abkhazia is tempting.