Semana Santa is the week before Easter (Easter is April 1st) and it would be great to be in Leon or Granada to see the festivities. Granada makes sense maybe as this will be the end of your trip (nice day trips: volcano Masaya, volcano Mombacho, Laguna de Apoyo (but could be very busy) and off the beaten path Chocoyero-El Brujo). And as mentioned above, any homestay that week would probably indeed be very special too. The week before Easter and especially Thursday to Easter Sunday beaches will be packed. Crazy busy. I have heard that goes for any body of water and that Ometepe would be busy too but I have no first-hand information.

I like Ometepe but 3-4 days would be good depending on whether you would be hiking up a volcano and on whether you would be doing a homestay.

No-

Curious- why are you going all the way to the BF's? Without seeing CR/Nica?

You need to go all the way to Managua first. Then a bus to Rama, and then boat to BF. Or, if possible, and a more fluid schedule needed, via Los Chiles/San Carlos down the Rio San Juan via Greytown.

Buses
Cahuita to SJ 4 hours
SJ to Managua 11 hours ish
Managua to Rama 6 hours ish
Boat to BF

Or, bus to San Jose, bus to Los Chiles, cross border, boat across RSJ, get to San Carlos, stamped in Nicaragua, the then a slow or fat boat down Rio San Juan to BF. This requires a fluid schedule from San Carlos on the Nica side, as boats may not run frequently, and or not have fuel.

I would also be sure to check the security and safety conditions in BF before you embark, and possibly along the Rio San Juan, as a lot has changed in Nica since the civil unrest, riots, crackdown and militia issues facing locals.

For getting to Managua from Cahuita, you would take a bus from Cahuita to Limon and then to SJ. (4.5 hours).
There are direct buses between the capitals of San Jose and Managua, Tica bus is most popular, its about 6 hours to Nica border from SJ, then border formalities (1-2 hours) and then 2 hours to Managua.

From Managua to Rama about 6 hours.

Obviously, this is a 3 day trip, as you dont want to get into Managua at late, you want to cross borders by 3PM, and you dont want get stuck in Rama.

If you break up the trip with National Parks, landscapes, towns, cities and beaches, it could be a nice 1 week trip easy, or more, just between Cahuita and Managua, with Tortuguero, Sarapiqui, Arenal, Rincon, or Tenerio as options, for going to Los Chiles crossing.

There are many buses running from SJ to Liberia, about 4 hours, and then buses run every 20-30 minutes from Liberia to Nica border in daylight, about 2 hours. Once across border, most hire a taxi to San Jorge for boats to Ometepe (Security issues) and also or a hire taxi to San Jan Del Sur, an popular surf/party town on the Pacific. Or, from Rivas or taxi hire to Granada. Granada to Managua bus or shuttle.

The border crossing north of Tortuguero, near the mouth of the Rio Colorado, to Nicaragua side, via boat, is just for locals, no foreigners allowed/processed at Immigration there.

Might want to check Trip Advisor for boat schedules, security and safety issues, as this forum has been dead on Nicaragua overall, and few people go to the Bluefields even when Nicaragua was popular before the unrest/riots/crackdown last year.

https://wikitravel.org/en/Bluefields

https://centrocoasting.com/nicaragua/bluefields/

Colonial cities/history: Granada and Leon
Nature: all the volcanoes, the nature reserves in Las Penitas and Jiquilillo, the nature reserves near Esteli and Matagalpa, Ometepe, Laguna de Apoyo, Chocoyero-El Brujo...
Wildlife and birds: some wildlife on Ometepe, at Laguna de Apoyo, on volcano Mombacho,in the northern highlands. More at Chocoyero-El Brujo. Best spot: Rio San Juan (Los Guatuzos is great).
Petroglyphs: Ometepe
Beach: lots of choice but I like Las Penitas and Jiquilillo
Water: Laguna de Apoyo, Ometepe...
Get to know the people: do a homestay on Ometepe, in Miraflor near Esteli or in San Ramon near Matagalpa

You can just wing it. Be aware though that it does take time to visit the Rio San Juan. You can fly there (but only on Thursdays and Sundays). Or take the bus (6-7 hours from Managua). Once there you get around by boat. To get to Los Guatuzos it is a 4 hour boat ride from San Carlos and boats don't go daily. Check out Cabanas Caiman.

Depending on where you will be between Christmas and New Year you might want to book ahead. Like I said, beaches get very busy.

The logical place after Granada is Ometepe. It's a good idea to advance book lodging for Ometepe, at least for the first night(s). Not because it will be sold out in the weeks before easter, but because everything is so far apart on Ometepe, you can't just roll in and compare different hostels/hotels. The best area to stay is anywhere on the stretch between Playa Santo Domingo through Santa Cruz and Baigue.

It's unlikely you need to worry about Leon lodgings for Easter. Leon isn't going to be a destination for Central American people going on vacation. But Las Penitas beach 1/2 hour from Leon will be sold out that week.

As for the rest, you can do it in whichever order, going up to the northern highlands before or after Leon. You could include beaches too, just not beaches for Easter week unless you want to reserve now for lodging.

If you want to go down to Rio San Juan area, you'd save that for last, because the bus transport for San Carlos goes from/to Managua, and you need to return to Managua at the end for your flight home.

Hi TeachingAndTraveling - starting in Panamá and working your way north would also probably be in your favor with weather. Come October and November, it should be better in the north - though nothing is a guarantee anymore.

You've clearly put a lot of thought into this. I've never used SKYPE in the places you mention, but WiFi for general usage is pretty decent though not always reliable. For Granada, Hospedaje San Jorge would be nice and inexpensive for a couple of weeks. Include Ometepe on the way or to break-up your stay here.

Otherwise, definitely split your stay with León. For as touristy and made-over as Granada is, León is battered and better as the Revolutionary town. I've no idea what that looks like today, but León is my favorite place in Central America. You've also quick access to volcanoes; do yourself a favor and try the volcano boarding.

An alternative to El Tunco in ES is Jiquilillo in the northwest corner of Nicaragua. It's great for all levels of surf, but is not a place you come if needing WiFi. Rancho Esperanza is my 'Go to...' place. Here's other info for all these places from Nicaragua in 2015.

If you would consider getting between Nicaragua and El Salvador using public transportation, instead of shuttle service, here's another Trip Report for something very unique in Central America - since you've an interest in caves.

Copán is worth a week of your Antigua time as is the lake at Atítlan. Someone needs to verify if they've ever used SKYPE, but I've never had internet problems for basic stuff. And since you have intermediate-level Spanish and will have already been using it for months, I'm not sure how beneficial Spanish lessons would be at this point unless looking to fine tune grammar or work on verb tense conjugations.

You've really something to look forward to; Enjoy ~

Rent for the north area Matagulpa.. Get in MGA and drop in Granada.

Just taxi hire the rest... Easier, less hassle, more relaxing and cheaper. Rent mopeds on Ometepe.

Ometepe to Leon is not that bad. It all sounds complicated but it is really not. Often a bus to Managua is waiting for the ferry in San Jorge but if there is no bus it is a short taxi ride to the Rivas bus terminal for a bus to Managua. In Managua take a taxi to the UCA for a minibus to Leon. But if you want to take a shuttle Bigfoot has one from Rivas at 10 am. There may be other shuttles but Nicaragua just does not seem to have the same shuttle availability as Guatemala or Costa Rica. Ask your hotel on Ometepe. You could take a taxi from San Jorge to the UCA bus station in Managua and then a minibus to Leon. But that would of course be much more expensive than taking a bus. $70 maybe?

We took a taxi from Leon to the airport. That was $60 4 years ago so I assume it would be $70 or so now. Just ask your hotel in Leon to arrange a taxi for you.

Many thanks for the suggestions. It’s definitely focused my mind to go Granada, Ometepe, Northern Highlands, Léon, Río San Juan. I would have liked a couple of beach days (I can’t cope with too much beach) but as I’m going to be in Léon over Semana Santa I think I might be giving them a miss.
I find it really difficult to book places out of the country so am agonising about where to stay on Ometepe. Has anyone stayed with Puerta del Sol (2km outside Moyogalpa)? A home stay appeals but I don’t know whether I might wish I’d stayed on another part of the island!
I’m booked into a hostel in Léon from the Wed of Semana Santa. Am I going to have problems with public transport from Matagalpa?

Many thanks again for the help