The shore dive from hotel Villablanca to hotel Caribe Blu is nice (along the Villablanca reef). It's about a 10 minute walk, and about a 1-hour dive. You stroll on in at Papa Hogs (across the street from Villablanca), and there's a little channel to crawl back out at Caribe Blue. It's only a $3 cab ride, but I walked my tank down (I must be an idiot).
That was my first shore dive, and my first drift dive, and my first night dive all rolled up in to one. Lucky for me, I found a great group of folks down from Iowa who were staying at Caribe Blu and invited me along (maybe I invited myself?). I would not have been that adventurous otherwise. They all had strobes, tank lights, etc., it was very well organized.
I also ran into a couple who did the exact same night dive on their own. I have no idea how they figured out when to come up -- they said they just popped their heads up after a while and looked around for the lights on the hotel. God bless 'em. Not me. Good luck trying to find your own way out, especially at night. You miss that exit point and your one-hour drift dive might get unexpectedly extended for to couple days or weeks, with an exit point somewhere in Cancun.