10 days would be more than enough time for the Peruvian Amazon.

Have you been to Corovado in the Osa? Much more rustic than the lodges you mentioned.

The other places that are known for their intense biodiversity are La Moskitia in Honduras and the Darien Gap in Panama. But, both are 'roughing it' locations.

Hi Lisa, our interests are similar. Look into Panama! We really enjoyed it after a couple great trips to Costa Rica. Great hiking in the mountainous area around Boquete. Look at Los Quetzales lodging, also Coffee Estates Inn. Fun to stay at other working coffee plantations. It's just a beautiful area up there by the border with CR. In and around Panama City itself is very interesting - you can take a cab to Gamboa area for some good walks and wildlife viewing. Panama is easy to get to- and easier to get around in perhaps than CR. Panama City is a much more interesting and fun capital city than SJ. Even has some good restaurants. I've been to Dominica long ago - just a day trip over from Guadeloupe. Did a nice jungle walk - didn't see that much though. Could be luck of the draw. It's very small..

Know you've nixed SA because of short time available, but did you know Avianca has a direct flight from DC to Bogota? Takes only 5 hours or so. No time change. We were in Colombia for 2 months this winter - gorgeous scenery, fabulous birds and other wildlife. Highly recommend it - if not for this trip - then another. Also - Napo Wildlife Center in Ecuador. . .

I'm with RAC. We loved the Osa, too, because it was the part of Costa Rica that most reminded us of the Amazon. No snorkeling there, though. Although I did swim in the river with my kids while my husband was fishing nearby from our boat for Pirhana. Now that's an experience. (Most of the time they won't bother you.)

The Tortuguero area is pretty wild and unspoiled, and the wildlife reminded me a lot of the Osa. Tortuga Lodge is a nice upscale spot with great food and wonderful service. To me, I'd rather go during turtle season though. We saw a lot of amazing wildlife - toucans, parrots, monkeys, crocs, poison dart frogs, otters, caimans, etc. Lots of great photo ops. It's primarily a canal based environment though so mostly boating and kayaking vs. hiking.

Forgot to add to RACs mention of Darien. We went there on one of our Panama trips and highly recommend that as well for wildlife viewing and hiking. But as RAC said it's roughing it - and not inexpensive. Best is to go with Ancon Expeditions - fly on small plane to grass landing strip at Cano. 13 hours walk to nearest town! no roads in. just jungle. A bunkhouse lodge - simple beds and shared baths. Dining gazebo.
Good simple food. Electricity just till dark. Wonderful!

We were in Panama this spring and loved it! Panama has some interesting history, compared with CR, and it was kinda cool to see the contrast of old colonial PC and glittering Chicago-style skyscrapers across the bay, viewed from our rooftop patio in old Casco Viejo. We got a birding guide to take us into Soberania national park and it was outstanding! You could check into the Canopy Tower and the Rainforest Discovery Center. The Smithsonian tropical research institure is there and you can visit that. A more-visited place with some really terrific snorkeling was Bocas del Toro, which we flew to from PC. Look into Jampan tours for snorkeling there. The town itself isn't much to speak of (more of a party place), but Bocas is an archipelago and there are some really cool places to stay outside of town (Tesoro Escondido, Playa Bluff Lodge)or on outer islands (esp. Bastimentos Island with La Loma Jungle Lodge and Casa Cayuco). Took a cool trip in a dugout (cayuca) canoe to an indigenous village. Lots of great birds, butterflies, monkeys and flowers were seen and hospitality, esp. at Tesoro Escondido, was fantastic.