If you're going to Mexico I would go to Mexico City, it's my favorite city I've been to in the world but there's no beach so that's not what you're looking for. I don't like sitting at the beach or pool and I don't like golf...
When I travel I like seeing everything there is to see, eating and drinking everything, and immersing myself in the culture. I've been to Cancun and for beach/pool sitting it's fine but there's better options in Mexico. I've never been but my buddy and his wife love Playa del Carmen and go all the time. Another friend went to Puerto Vallarta for the first time and liked it so much he bought a house there which he goes to months at a time and he'll retire to. As imno1 said there's also Cabo.
Italy, Spain, and France are great but the only one I've been to the beaches at was Italy and it wasn't good for that. Italy is all about exploring the cities and small towns in the countryside. I saw the beaches in Nice, France and they looked really nice but I didn't spend any time at them. I've heard from friends Portugal and Greece are great for the beaches/coast. I've heard Croatia is even better. That will be my next trip, Croatia and Serbia.