Ive been there a few times, while traveling in mexico...
eat at fajita republic...its hard to find but well worth it, its in viejo vallarta. Conchas Chinas beach is the best for swimming, I think it might be considered private, but I was never shoooed away, sea shells are awesome there, so are the houses, its a short hike past muertos beach as far south as you can get....in other words, facing the water on the beach turn left and keep going, just follow the path...
If you aren't staying in viejo vallarta, old town, make sure you take the local bus there and at least walk around through all the shops....
Vallarta is by far my favorite place in all of mexico, the yucatan honestly just doesn't compare.... The bay faces west, so the sunsets are awesome....have fun!