I live in Wilco. Definitely mostly sprawl, but there are efforts for urbanization in a couple of ways. Baby steps, but some promising developments that may spur on other opportunities a la very small versions of the Domain.
Cedar Park is redeveloping
Bell Blvd and has also pushed for more density in apartment buildings and shopping areas in recent years that will perhaps yield some changes.
Leander has
Northline, right next to the Leander Red Line Station. This also has an adjacent St. David's hospital (clinic and ER currently, but I think it will be expanded) and an ACC campus.
Leander also has another significant proposal immediately to the south of Norhtline, called
Leander Springs. Not sure how far along that is in the approval process.
Round Rock and Georgetown have small-town downtown areas, but with some charm and character. I have heard rumors of increased density but on a much smaller scale. Haven't heard much beyond these things.