I would think that UT would have more national portability, and both would have much more than WUSTL. UT has higher rep scores in USNWR, but this article shows relative equality in hiring (http://www.law.com/jsp/nlj/PubArticleNLJ.jsp?id=1168423325385).Some other resources are Ciolli's study on xoxo and nalpdirectory.com. Good luck.
I think both are roughly equivalent in their national portability. It may appear at first glance that UT has more pull nationally, but that is likely due to the high number of individuals that stay in CA after attending USC. The high number of USC grads that stay in state is probably a reflection of the more profitable legal markets available in CA compared to TX. Both are great schools that will not significantly limit your ability to be hired almost anywhere in the country as long as you're willing to do a little extra legwork if the places you want to go don't heavily recruit during OCI at whichever school you choose. By the way, I second your love of Chicago!