harriette -
ha ha barb knows me too well! i recommend la casita as well - stayed there twice. yeah, it gets hot during the day, but we were only super hot while at the ruins. if you all dont mind steps, the river is a wonderful cool off during the day. nights were fine. we didn't need jackets.
we kept the doors open a lot, and lil flying critters do get in. hope your friends are ok with that.
http://www.pbase.com/sweetjane/belize_mainland_07i was there last may 18th thru 23rd. ask me anything you want that barb and elbert haven't already answered.