After extensive reading on this forum and some advice from other readers which has been extraordinarily helpful, I've created the following itinerary for an August visit with two active 8 year olds. Any comments/suggestions/activity or guide recommendations would be appreciated.
Day 1 SJO, pick up rental car, Xandari for 2 nights, visit Zoo Avenue
Day 2 Day trip to Poas Volcano, LaPaz Waterfall Garden and possibly Toucan Rescue Ranch
Day 3 Drive to Puerto Viejo--Le Cameleon for 3 nights
Day 4 Sloth and Jaguar Shelters/beach
Day 5 Snorkeling at Cahuita (assuming water is clear)/beach
Day 6 Drive to Pavona--take boat to Tortuguero--Tortuga Lodge 2 nights
Day 7 Tortuguero
Day 8 Boat/drive Pavona to Sarapiqui--Selva Verde 2 nights (alternatively, could do Monteverde on the backside of Arenal/LaFortuna instead--comments welcome.
Day 9 La Selva/Tirimbina Chocolate Tour/possible raft trip
Day 10 Drive to Arenal/La Fortuna--stay 4 nights--looking at Springs, but currently Tabacon and Nayara have much better deals
Days 10-14 Proyecto Asis animal shelter, Sky Trek zip-lining, La Fortuna waterfall hike, Hanging Bridges hike, La Roca waterfall rappelling, Eco Termales hot springs and possibly Cano Negro
Day 14--Drive to Xantari 1 night
Day 15 SJO