I have been to Mexico, but not Las Vegas but have been to many other places in America. The place we stayed at in Mexico is called Playa del Carmen on the Yucatan Peninsular. So many places to see nearby including the ancient Mayan site of Chichen Itza, which the locals call Chicken and Pizza which, I think, is a World Heritage site. Another Mayan ruin we visited was a place called Tulum set above the most wonderful beach and I recently read somewhere or other this had been voted one of the most beautiful beaches in the world, it certainly didn't disappoint. We also went to two very interesting eco parks, both fairly nearby, Xcaret and Xel ha (lot of Xs in Mayan) plenty to see at both these places as far as wildlife and marine life are concerned. My son, who was with us went snorkeling, the coral reef we were told, is second only to The Great Barrier Reef and the fish are very beautiful. I would absolutely recommend Mexico to anyone, the Mexicans were very hospitable. I don't know when you are thinking of going suzz we went in December, we had very good weather. One of my sons went last October and found it a bit rainy and overcast. I would quite like to go again or possibly somewhere else in Central America such as Costa Rica, have enduring memories of some of the fantastic wildlife such as very large Iguanas that came out midday to bask in the sun and strange little rodent families that scuttled around called patchas, not frightening like rats I hasten to add.
Whatever you decide have a great time.