Bob, talk to me about lodging -- I have an "in" on a condo in Puerto Aventuras that is about as cheap as you could ask for -- 2 bedroom, so if you can find a companion for the trip, you can split the already low rent.
The caves that are interesting to dive run from about Puerto Aventuras to 10 or 15 kilometers south of Tulum. Most of the ones I really like to dive are south, but if you base out of PA, you can use Zero G for gas, and their prices are very reasonable and their gas is reliable. There are now a couple of shops pumping gas in Tulum (I believe Xibalba and Protec are -- Cave Heaven's compressor isn't on line) but I trust ZG.
If you don't have a buddy or buddies who have been there before, by all means hire a guide. Jason's a great one; Natalie Gibb is another, and Ela Bertoni (formerly of Cave Heaven) is a really fun gal, too. And all three dive sidemount, if that matters. The reason for hiring a guide is more to avoid frustration than anything else -- just getting to and getting INTO some of the sites is a pain if you don't know how it's done, and finding the main line can waste a whole dive. Most guides charge in the neighborhood of $200 a day, but that includes tank rental and entry fees, which will run $40 to $50 a day -- and if you are working with a guide, you may not have to rent a car, which will save you a minimum of $250 to $300 for a week. Guiding fees also go down if they have more than one client. Jason lives in PA (and actually, he rents the other room in his house, so that's another lodging option), and Natalie is in Akumal, and either would pick you up where you are staying.
You can't go wrong with the caves. Some are more decorated than others; some have more halocline, or huge spaces. For example, I'd highly recommend doing Taj at the beginning of the trip, because there are some HUGE, halocline-filled spaces, where you can enjoy the fiberoptic effect of the lights being spilled in a bright line on the far cave wall. It's also a good shakedown dive, because there isn't anything very small or difficult, which is nice when you are shaking down the weight and balance of a new setup. (Everybody dives Al80's down there, almost without exception.) I LOVE Grand Cenote -- you really could spend an entire week in there and not see everything that there is to see, and it's all different. Jailhouse is an amazing place, and one of Peter's favorites for taking pictures. Pet Cemetery to the Blue Abyss is an amazing dive; Chan Hol has fabulous places to poke around in. And EVERYBODY needs to dive NoHoch at least a couple of times, just for the "wow" factor of being in a cave that looks like a madman good loose with an industrial frosting machine.
We should go for a dive one of these days and have a drink afterwards and talk about this. Sorry I can't say I will be down there when you're going, but my travel plans for next year are entirely on hold until we sort out my job situation.
