I stayed at Mopan RR last April, it was very nice...you'll be pampered. Do ask for an air conditioned cabana as it gets very humid during the day. You can turn off ac at night, sleep with just the screens and hear the wonderful jungle sounds, very soothing. Hey, they even have special lighting to create ambience just with the inner thatch roof lit up softly, very romantic. Here's photos from the resort:
http://pg.photos.yahoo.com/ph/cayephotos/album?.dir=53d4&.src=ph&store=&prodid=&.done=http%3a//photos.yahoo.com/ph//my_photos
Hope you get Sheila the Toucan to take tidbits from you!! Francisco is a fun guide for excursions, too.