Mercada 28 is a local market for tourist where you can buy souvenirs, talk to the locals, and eat real mexican food. Any bus will take you there, it's in the opposite walking direction from Walmart. Usually locals will show you the way. Mercada 23 is a bit farther, smaller and not for tourists, only for local people, I do recommend visiting to see the local culture and try out what the locals eat.
I considered taking Morgan for a nice meal off resort one evening to La Parilla, I don't know why though but i felt uneasy so we didnt bother. This year however a few of the hotties and hellraisers group have decided we're all going for a meal one night!
We've taken the bus ($1 US each way) to La Isla which is a beautiful mall. It's only a few, maybe 10 minutes away and the bus ride is actually pretty fun! It's bumpy + fast. The bus and La Isla are very safe for tourists. La Isla is also a good way to get wifi. Sometimes we've gotten free wifi just by standing in the right spot. You can also buy a drink from the Starbucks there and the receipt will have a wifi password.
We've been off the resort for a walking trip to the local shops and never felt threatened at all. Xel-hah is a lot of fun. It's a nature preserve so you have a beach, snorkeling, zip lines, cliff diving (small ones), bikes etc. it includes breakfast and lunch and adult beverages.
By the way Temptation doesn't have an "s" at the end of it. There is a huge thread that just got resurfaced after a year.
Don't feel bad I got busted for that too. I'm not sure if it was me or the the spell check. If you capitalize the "T" it wants to add the "s" to make it the Motown group.