Planning a trip to Costa Rica in December for a group of friends. If you've been before, I could use YOUR help!

• What: Trip to Costa Rica
• When: Over Christmas / New Years (roughly two week window)
• Who: Me, my girlfriend, and about 8 others.

I would love any tips on travel agents, airfare (I will probably use FlightFox), where to stay, excursions, getting around, local customs, things to watch out for, the best things to do or see, etc. Since we are coming from the U.S. and going about 10-14 days, we would probably like to change where we stay about halfway through to mix it up. Given the size of our group, would it be good to try and get something that can accommodate all of us vs separate living accommodations by couple? We've traveled like that in the past (i.e. rent a house) and that worked well for us. Ultimately, I'd like to plan out as much of the trip in advance as reasonable including getting around so we are not winging it when we get there. Not everybody in the group is an experienced traveler abroad and so having tour guides and transportation worked out might be the most ideal scenario for us.

Some suggestions I've already gotten from friends are:

• Chachagua Rainforest Hotel & Hacienda
• Nayara Hotel, Spa, and Gardens overlooking the Arenal volcano
• Desafio for excursions.

If you have any experiences with the above or can share anything about your adventures in Costa Rica, please reply!