My family and I have been to Schlitterbahn many times and its always a good time. Our most recent visit was no exception. Besides the obvious reasons like free parking, free tubes & the fact that they allow you to bring a cooler in, i love Schlitterbahn because they have tons of shaded tables and it never seems overcrowded.
My kids are both under the age of 5 so we just hang out in the kiddie area all day, and i have never once worried that i would lose my kids. There is so many different options for the little ones, that one thing is never too crowded. When we get tired, we go back to our nicely shaded table and eat lunch that doesn't cost a fortune because we brought it with us!!
If your in the Central Texas area, and you have not been to Schlitterbahn, you should plan your trip. Its a good place for kids of all ages!!