RE: So how much time do you recommend in each place?

Managua has much more than nothing to see. Especially if you use it as a hub for day trips. If you buy into the hype that its a big evil scary city there are plenty of great places to stay on the outskirts. Swim in laguna xiloa, go to the chocoyero reserve, volcan masaya is 15 km away, take a boat tour of the big lake, there are beaches less than an hour away. You said you like hot springs, the tipitapa hot springa are only a couple of kms from the area.

For hot springs, jungle/nature hikes, and kayaking you may wanna think about going north for a couple days. Somoto canyon, the estanzuela reserve, selva negra, teustepe hot springs etc
Thats where that stuff is located.
Plaves like granada and even leon to a smaller extent are tourist spots. They lack the same culture and authenticity. Not much for jungle hikes in the granada area. Though if you are into history you might be into it cause it definitely has that.

Also i love ometepe, but 5 nights is a good long stay there unless there are specific things you are going for and like relaxing and slow. I would recommend cutting a day from ometepe, and granada, maybe evenleon and add another destination in the north for 2 or 3 days.

I would get out of the capital city asap, no need to use as a base, use Massaya or Granada.

With 18 days, what about the North? Estelli area? 4 nights Granada is 2 too many IMO. What about a few beach days near Leon? How about Corn Islands? What about Solentiname Islands?What about the Rio San Juan River, and San Carlos and El Castillo, and the refuges?

Do you have a guidebook? Moon is best for Nicaragua.

Aww Amigo,,,I missed that...jaa jaa

You might add Matagalpa for some hikes at Selva Negra and Cerro Apante, soaking up local life without all the tourists...have fun..

Thanks everyone. We were thinking of the Corn Islands but my partner is a tad reticent to go all the way over there as she (we) had a not so great experience on the Carribbean side of Costa Rica.

So Granada is only two days worthy? How many in Leon or can we (or should) we use it for a base. We'll take one day off Ometepe. We were attracted by the horse riding and kayaking at the Finca we intend to stay at.

Tell me about these northern hot springs anyone and how long we should stay?

I have the Moon guide on order and the new LP that just came out. I willl look up the other places you recommended.

We did the Rio San Juan when were we in CR and went all the way to the Nica border. Though amazing, we have seen it (saw thumbnail sized bats and a baby albino new born monkey hanging by her tail looking right over the boat while slowly spinning - she thought we were pretty interesting things to look at)

Thanks!

-Findley

What beaches do you guys recommend near Leon. I think despite the attractive "pink sand" of San Juan Del Sur we'll give it ai miss as touristy.

las penitas is the easiest to get to, about 20 minutes from leon. nice places to stay there.

If you are going to skip dan juan del sur because its too touristy, you probably will want to skip granada and leon too.

I can't comment on all the spots, but we went to Granada and Nicaragua and would suggest that both need at least 3 days. Close to Granada you have the Masaya volcano and Laguna de Apoyo which are worth visiting: http://bbqboy.net/granada-nicaragua/.
Love Omepete: http://bbqboy.net/isla-omepete-nicaragua/. You might want to skip the Maderas hike as I suggest in there. I've heard Concepcion has better views but a really tough hike...

Have a great time, Nicaragua is really nice (we didn't like Costa Rica either by the way, think you made the right decision).

Frank