My mom and brother moved to Belize (San Pedro) about 6 months ago. It's a fun and fantastic place, although at first you'll think "WTF?" It's not especially pretty, it's kinda (well, ok, very) third world and you really can't see what all the fuss is about. Second day, a bit less, yeah, ok you kinda see what the expats are talking about... where's my beer? (Belikin is goooooood!) and by the 3rd day you've lost your shoes and forgot about all the crap back home in the States...
Seriously, Belize is no big deal. Easy in, easy out, just remember you have to pay the departure tax in US dollars ($40). Not Belizian. The exchange rate is 2:1 (officially it's 1.98:1, but everyone just goes 2:1). US dollars are universally accepted. English is the official language, but just like in Miami, you might get more done if you speak at least a little Spanish.
Show Tropic Air your company ID- you might be able to jumpseat for free with them. Otherwise, you should get a discount on their flights (I think San Pedro cost me $40 each way).
I've been to Belize 3 times now (for a month back in Feb) and I always have a great time, although somehow I never made it out of San Pedro. (Well, I did go to Caye Caulker for Lobster Fest- all you can eat for $7- who wouldn't?) Never did go scuba diving, but my sister did, and the night dive is spectacular. Especially with the bio-luminescent sea algae. I gotta go do it next time... Every time I go, I come this close to just chucking it all and getting a job with Tropic or Maya Air. Flying into the jungle sounds like a lot of fun.
I don't know who you can JS on, but Continental, Delta, AA and USAir all fly into there.
PM me if you have any other questions...