I recommend that you trek the EBC solo(rather than with a group), if you can afford it, particularly if you are going to hire a guide and porter. This way you can travel at your own pace rather than the pace of a group. If you want an extra day in a particular place because you like it or because you are sick, it's easy to do solo. Otherwise, the group will push on and you need to decide if you want to push on with the group or stay behind or go down (usually with a staff member from the group). If you want to meet other trekkers along the way, it's very easy to do so in the teahouses in the evenings. If you make new friends that you want to trek with for a few days, it's easy to arrange to trek with them. If you get tired of them or want to meet other friends or just trek by yourself, it's easy to do so. Further, let your guide know ahead of time about your expectations. If you want to trek by yourself and just want your guide to keep an eye on you, let the guide know. If you want the guide to hang with you and tell you stories or educate you about the culture, religion, and scenery, let him know that too. I remember my first trek to Nepal 15 years ago where my guide would play a recorder as I trekked with a friend. It was delightful and he was pretty good! Further, I learned so much from him.

If you haven't hired your guide yet and you want some recommendations, send me a private message by clicking on my name to the left of this message, and I'll recommend three locally based trekking companies, based in Kathmandu. Over the years, I have met several Nepal friends that have started their own trekking companies.

The key to acclimating properly is to slowly acclimate. Generally, your sleeping elevation should not increase over 300 to 500 meters per night once you are above 3000 meters . Sleeping elevation is so important because you spend so much time sleeping. Most people fly into Lukla and then trek for a few hours before stopping for the night. The next day they trek to Namche (3440 m) where they will spend two nights acclimating. Then, just slowly work your way up to EBC, stopping for the night every 300 to 500 m in elevation gain. Some of your trekking days will be quite short.

At Tengboche (3870m), the average day maximum for December is 7 C. The night low average is - 7 C. The weather is usually clear in December so expect sunny days. When you are trekking, the sun will feel warmer than 7 C. At the Pyramid Research stations outside of Lobuche (5000m), the December maximum average high is around 0 C. The average minimum low for December is - 12 C. https://drive.google.com/drive/folders/0B6Sn11ZTBrhvV3ZFQVgzX2pIVlE
http://www.evk2cnr.org/cms/en/evk2cnr_committee/presentation/
If you are into science, it's worth a side trip to the research station, if they are open.

Finally, did you do your Trans siberian/ trans Mongolian rail trip? I was looking at your profile. I plan to do a similiar trip this May. I will send you a private message asking some questions, if you did it.

"China, Vietnam, Laos, Cambodia, Thailand, India, Nepal and Mongolia to then go into Russia to take the Trans-Siberian Railway. "

Thailand, India

Traveling through Burma is difficult, particularly with the atrocities/refugee crisis on the border right now. Best to fly from Thailand into Yangon and then Yangon to somewhere in India. Or just fly Bangkok to India.

Nepal and Mongolia

I assume you are considering going through China a second time?

Chinese visas are typically SINGLE entry. You will need to find somewhere to get an additional visa.

To cross from Nepal into China you will be going into the Tibet Autonomous Region(TAR), which has heavy restrictions on travel. You need to travel through the TAR as part of a tour, and if you enter by land or air from Nepal you will need to be on that tour for the duration of your trip in China. Probably best to fly from Nepal to somewhere else in China, do a loop to Lhasa if you want to see Tibet, and then continue through China. Alternatively you can go from China into the TAR and then exit into Nepal, reversing your loop

Your other option is into Pakistan and then into China. The pass is often closed to foreigners.

You could also go through Afghanistan then into Tajikistan or Uzbekistan(get a visa well in advance) and then into Kazakstan(Kyrgizstan if you like) and then Russia. From there you could take the trans-siberian in either direction.

Mongolia to then go into Russia to take the Trans-Siberian Railway. "

The Trans Siberian goes from Vladivostok to Moscow and does not enter Mongolia. The trans mongolian goes through Mongolia.

Which way are you planning on taking the Trans-Siberian? Where will you be starting/ending.

All good practice. The Trans Siberian is the next on his hit list. He's done SEA , China and Tibet and is looking for a bit more excitement. Just a thought. Does the main LP web site have anything in their Destinations etc sections?

Right. Forget Vietnam and China. Has no bearing on the actual Trans Siberian trip. And as I said, this isn't the right branch fr it except finding an Australian travel agent. But if it was me, I would still contact realrussia.
And while I am at it, you have given incorrect info about Chinese visas.

Vietnam is part of the pre Sib travel westy as in OP " I'm planning a trip through Vietnam, China, Mongolia and Russia on the Trans Siberian rail network. "
I think you need to interpret the and as a separation but part of his six weeks before getting to the station.

Hi all,

So I'm visiting 13th - 31st December and I've tied myself in absolute knots reading travel advice for this time "dont go here, its too cold..." and "If you don't see that, you're not seeing real China".

China is fine in December. It can be cold and/or polluted but rain is uncommon and at least in Beijing you can always pray for Siberian or arctic blasts of cold air to bring crystal clear skies.

First I'd say you appear to be packing too much in. China is a huge place and even with flights or high speed trains, it takes a while to get anywhere. Dont jump around too much or try to cram in too many sites.

Day 1-4 Beijing

Depending on what time you arrive and how jet lag is you might want more time in Beijing. 3-4 full days is not overkill.

Day 5 - Travel to Pingyao (I know its not a full day travelling but I dont want to be rushing from train station to sights and in my experience in many other countries I dont sleep well on the night train).
Day 6-7 Pingyao

2 days and a travel day in Pingyao is too much. It's a lovely town and there are some sights outside of the walls, but it's 6-8 maybe 10 hours of stuff to do. Not 30-40

Day 8 - Travel to Chengdu
Day 9-10 - Chengdu (pandas!)

There are pandas all over China. Chengdu is a great jumping off point for all sorts of amazing stuff in Sichuan, but if you are just interested in Pandas I reccomend you pick some place else.

Day 11 - Flight to Yangshuo
Day 12-14 - Yangshuo

Yangshuo is but one possibility if you want a glimpse at once rural china, now touristy China. I wouldnt jump around to much if I found sometihng else I could sub in.

Day 15-18 - Hong Kong and Macau.

I really like Hong Kong and Macau. For me though they are different destinations. I try to hit them up more on my way through other parts of Asia, rather than including them in a China trip.

The only bit that bothers me is Yangshuo - In December I envision it as a very quiet place, the rivers too low to go on a bamboo raft, the weathers too cold to cycle and enjoy the scenery, etc...

Any feedback at all appreciated.

Thanks!