Go to Fort Worth. It isn't just for cowboys and you'll have a better time. Fort Worth has some of the best museums in the southwest (Amon G. Carter, Kimbal Art Museum (which has a large egyption exhibit going on right now), Modern Art museum, and the Science Museum with omni theater). The Fort Worth Zoo was rated in the top 10 in the country. I liked it better than the San Diego zoo because you could actually see the animals awake. Downtown Fort Worth has really good night time activities. The Sundance Square area has several night clubs and restaurants, and movie theatres. If you want cowboy stuff, go to the northside to the stockyards where you have Billy Bobs and several other bars, restaurants, western themed shops, Steam locomotive rides, etc. If you want to know more, just pm me.
Edit: Oh and I forgot to mention the Botanical Gardens which will also be doing a fireworks display synchronized to music, and the water gardens (famous for being filmed in Logans Run).