I'm not an expert - this was my 1st time in AC and Belize, however I was highly pleased with Banana Beach. The rooms, pool, service were terrific. Also, they have a tour company on site - Monkey Business. They will arrange your tours. By all means do the zip line in the morning then do the cave tubing after. Take a disposable water proof camera with you (cheaper to buy in the mainland US - don't know about Alaska)
For snorkling Hol Chan and Shark Ray Alley, ask for Li'l Alfonso. He's a local who knows the sealife, is personable and obviously loves and respects the sea critters. He'll show you how to hold a nurse shark if you so desire.
For diving - I did two dives with Amigos Del Mar; they're definitely a class act. I hope to dive with them again.
Ask on this chat room what others have to say about their lodgings - I read lots of reviews B4 I made my choice and don't regret it. Have fun!