Planes now are safer than ever. And flights to resort areas have the happiest flyers anywhere, which makes the environment a lot better. Get a few drinks and strike up some conversations with neighboring strangers. You’ll learn a lot and be there before you know it.
In Mexico, even the locals don’t drink the water and they are suspicious of salads that they didn’t prepare themselves. The salad tip is a good one. The only time I ever stayed at a resort was in Cabo and can confirm the drinks where we stayed were also mixed strong - which made me happy. I’ll also echo the comments about not being afraid to do things outside of the resort. Do your research before you go. Some have online booking now.
If you go to Cancun, you can pop over to Cozumel, rent a scooter, and cruise around the entirety of the island. There’s a cool chocolate shop and some smaller ruins sites there that are cool to explore.
You’re going to have to haggle like a mofo to buy souvenirs. Obvious tourist = at least double price. If you can’t get it for at half price, you haven’t negotiated hard enough. Everyone here hates low-ballers, but that’s exactly what you need to be to get a ‘normal’ price at a shop near a resort area. Have cash and be ready to walk away if terms aren’t met quickly.