If you really want to make it a two-day trip, I'd detour a bit to the north of IH10 and stop in Round Top or Brenham. Both are nice little towns with some interesting things to see. Round Top has a number of art galleries/studios and antiques stores. There are also some nice small hotels, B&Bs, and good restaurants. It's also the home of the Winedale Historical Center, where, if you're there at the right time, you can see Shakespeare performed in a barn by a company of acting students from the University of Texas. I'm not as familiar with Brenham, but friends tell me that it also is a pleasant place for a short visit, as long as you aren't looking for big-city entertainment.