I think the plane has been mostly gone for some time. Did you dive it recently? I never have, but heard that there wasn't much to it back in 2005ish, and then read somewhere that Wilma took care of what was left.
A little more about Casa del Mar: It's resort like, but not really swank. Usually lots of divers there. If you wanted to treat yourself, get a cabana. They're separate from the main building, pool deck level and have small refrigerators and a little kitchen with two bedrooms and two bathrooms.
Casa del Mar is an 80 peso cab ride, one way, to the square. The food in the Casa del Mar restaurant is just fine. The menu is small, but there are lots of good choices. I've never stayed AI but eat most lunches there and a few suppers during a 2 week stay. If the restaurant is X full they have a breakfast buffet with an omelet station. The "breakfast meat" on the buffet is cut up hot dogs, which I happen to love. BIG fan of the Queso Fundido, the whole fried fish and their Club Sandwich. I've liked everything I've tried.
If you eat breakfast and lunch there, and have 4-5 drinks, you've about paid for the AI.
Ultra convenience? Stay at Tan Kah Village and dive with Scuba Shack. You can put your feet on the ground out of bed, walk across the street, and walk right onto the dive boat. 150 feet total? They have a little cove so it's basically a level step onto their dive boats. If you stay at Casa del Mar, you'd have to go down about 5 or 6 steps from the restaurant and walk about 30 seconds longer. Cake. Actually easier than staying at Casa del Mar and getting picked up from the CDM pier.
Tan Kah Village doesn't have a restaurant. It's very small and rustic, with a pool. I don't think they have TVs in the rooms. I can't remember her last name, but Roberta owns both Tan Kah Village and Scuba Shack. She's there every day and is a great source of information on dining, etc.
Though I stay at Casa del Mar, I get most of my shore tanks at Scuba Shack and dive from their dock/cove. Very nice people. Did a week of boat diving with them years ago. Good dive operation. Nice dive locker room.