We were in Belize in Feb this year.
We flew from San Francisco to Belize international and then took a puddle jumper to Caye Caulker. You can also take a water taxi. It costs less but is 2 hours vs. 8 minutes.
Caye Caulker can be done cheap or expensive.
www.gocayecaulker.com is a great resource to scope out places to stay. We rented a nice cabana from Maxapin for 65 a night, but you can find nice places for as little as 15-20.

Go snorkling with Juni, he can be found across the street from the basketball court. $35.00
for an amazing adventure. Check my blog for the story.

We also stayed at Ian Anderson's Retreat and went to Tikal and did the ATM Cave. I could have skipped the 5 hour drive to Tikal, but don't miss the ATM Cave....best ruin's I've ever seen.

Good luck.

Astrid:
You'll be here in February...cool. It's a great time to be here, perfect weather and all. I read your expected log that you posted, and flying into Cancun is probably the best idea. I've had friends save up to $800 by flying into Cancun. Be sure and party in Cancun for a day; it can be over touristy, to say the least, but it still is a fun place to party, and the music there is the best; way better than what you'll here in Belize. The bus from Cancun to Chetumal is 5 or 6 hours, and it's a really nice bus; the busses in Mexico make Greyhound look like port a potties - who'd have thought? When crossing the border make sure you don't pay any exit tax to Mexico since you'll be flying out of Cancun too.
From Chetumal to Belize City will take 3 or so hours. Then you could take the water taxi to Caulker. One thing about Caulker...it's way small. I mean, I will never spend more than a night at a time there again. I'd recommend staying there maybe 2 nights. You must do Raggamuffin's Hol Chan Marine Reserve Tour. They kick ass, and Hol Chan is really neat with all the nurse sharks and sting rays(all very docile) I'm actually taking a bunch of students to Hol Chan again this weekend - do it a couple times a semester. Staying on Caulker - I always have people ask where is the cheapest, so I recommend Bella's Hostel, but it sounds like you might want something a little nicer...
You'll want to see Placencia, for sure. Caulker doesn't have a beach, in fact there's only one beach in Belize, and that's Placencia. I just won a long weekend in Placencia 'cos my Halloween costume was sooo kick ass. I try to do Placencia 3 or 4 times a year. There's a gelatto place there that's amazing!!! I swear a couple months ago we spent over $100 there in the course of one long weekend. I recommend Deb and Dave's Last Resort 'cos it's cool and rustic and quaint.
You might want to do Dangriga for a couple days, but some people don't like Dangriga that much. There are a lot of drummers there, and you'll hear some good drumming while there.
San Ignacio(Cayo) is the place to be. I noticed you mentioned the Ix Chel Wellness Center. My girlfriend starts there in a month. Rosita is way cool. A couple months ago in Placencia, we all stayed together and had an amazing time. I'm a Neuro-Muscular Therapist, so Rosita and I get along well. There's soooo much to do in Cayo that I don't see why people go anywhere else. Mountain Pine Ridge is kick ass; it has at least 6 major sights there, and Rio On Pools is why I bought a car! You can also horseback ride at Mountain Equestrian Trails. Caracol is a really neat ruin, and is the biggest in Belize. Barton Creek Cave and ATM cave are really neat too. There's also Cahal Pech and Xuanantunich in the way of smaller ruins. There's a ton of good places to eat and hang out in Cayo too. Check out my Best of Cayo page at: www.shc.edu.bz/marcus/cou...yobest.html
I see you mentioned Chaa Creek! I've given some massages there. The spa there is top notch. It's a neat place. I'm surprised it's not on the www.unusualhotelsoftheworld.com/ website yet. I recommend it and Parrot's Nest, which is right on the Mopan river, and is where I hang out a lot, and tube the river all the time. The Nest is also rustic and quaint, yet well priced, and for some reason doesn't have mosquitoes. I guarantee you'll see the over 20 iguanas at the same time on the riverbank there. Oh yeah, Chaa Creek has a Butterfly farm you'll want to check out. If you can, see the zoo. It's really neat to see the animals in their actual habitats and not in concrete pens. And while tubing the Mopan is awesome, the best tubing in Central America is at Jaguar Paw. Words won't do it justice.
Hope this helps. My number is 660.6336. You guys should give me a call, and we'll hit Mountain Pine Ridge or something. Rio On Pools rocks!
Peace out,
-MM

I must concur with the good doctor above... on many a great point. It must be a Cayo thing but I don't think so. In any event you will have fun and you don't have to mortgage your soul to do it... some serious fun here.

MA, in residence for 6 mos a year