Six Flags in Arlington is a must if you\'re into rollercoasters, they have some of the best.
I\'m located near Austin, you should check out 6th street. Lake Travis is popular, check out Carlos \'n Charlies or The Oasis....food sucks but there\'s plenty of people and entertainment on the weekends.
Going from Austin to San Antonio you\'ll go right by Schlitterbahn in New Braunsfels(sp?), one of my favorite waterparks.
San Antonio has the River Walk(which is a must), the Alamo, and Fiesta Texas.