Western Mexico (Yucatan and Quintana Roo) are fairly safe, touristy and developed. I'm not sure on resorts, we stayed at a few different ones with all inclusive and they're all pretty nice. Some might have slightly better customer service, some might have better amenities. There are basically three tiers: bargain bin which aren't that great, mid level which are probably what you want (look for age of construction) and then the ones for honey-mooners and people with loads of dough.
Keep in mind that in 2005, a huge hurricane came through and wiped out a lot of stuff and the rebuilt most of it in '06. So if you can find something like that, it should be fairly new and nice.