It looks like your trip is well-planned already. The Arizona-Sonora Desert Museum is outstanding. I don't think your east coast cave or the one at the Desert Museum are as exciting from an ecological/preservationist standpoint. They designed the entrance so visitors have to go through a series of airlocks, designed to prevent the moisture of the cave from escaping into the hot, dry Arizona air. Most caves open for tourists are no longer "living." But if you travel to Arizona frequently you might want to save Kartchner Caverns for another trip. It's a bit of a drive from Tuscon, and you may want to limit the amount of time you spend seated in a moving vehicle. Rental car trips in and around Tuscon and cramped airline seats might be enough for one trip. I'm big on museums, and the Tuscon Art Museum is good for a city of that size, and located in a neighborhood I enjoy strolling around and window shopping in. More artsy, less Scottsdale/Camelback shopping districts, if you get the comparison to Phoenix area shopping spots. If you or your husband are into aviation there's a museum there you might want to check out on one of your trips out there.
Lazing around in a pool, gazing at the mountains, sipping wine, it's all good. Have a great time.
Glad your son found a job on one coast, at least. Housing here is getting so expensive he's probably a lot better off financially where he is.