You can fly to Intercontinental (IAH) or Hobby (HOU). IAH is in north Houston and HOU is south. HOU is the hub for Southwest airlines. Being from Houston, I always try to use IAH.
For Easter, I got my mom a last minute flight to see my neices on Southwest. And while I like the price, going to the part of town where Hobby is, is almost not worth it for me. I dread going there next weekend to pick her up in the late evening. It is a part of town where you do NOT want to have car troubles or forget your cell.