I've never thought of the condo rental thing. There are some huge beach front Condos that I don't think you could turn into an Air B&B. I know nothing about the Air B&B business, when I think that I think older house, and a lot of that prime real estate got destroyed. GPT has a nice walkable down town, Biloxi has an assload of Casinos. Both have some shitty areas.
If you want a rental property for weekend getaway type places I would look towards the west side of Long Beach and Pass Christian.
White Cap is one of my favorites for classic gulf coast seafood.
If you don't like gambling, there is fishing, lots of good kayaking spots, and eating. We have some pretty diverse competitive shooting as well.