My wife and I will be staying on AC the last week in May. We plan to spend a couple of days on the mainland, returning to AC each day. Looking at all the material available, we'd like to see some ruins, go to the Belize zoo, and maybe do the cave tubing trip we've read about. Can all this be done in a couple of days? Is the cave trip worth the effort? Do you recommend the river cruise to the ruins, or some other option?