pigsinspace,
I would say that after UTSW, Baylor Dallas in another program that would offer an excellent 3 years of IM training and would set you up pretty well for fellowship if you planned to do one. As far as I know, they have three fellowships there themselves -- GI, Cards, and Heme-Onc. I could be mistaken. The training there is good, good mix of insured and indigent patients, and you see a lot of bread and butter along with some zebras. I think the only caveat there is that autonomy is somewhat curtailed as most decisions are run by an attending first. Whether this is good or bad depends on how much autonomy you want/need out of your training program. I don' t think a lack of autonomy has any bearing on the quality of a program -- it's just that it's more incumbent on the trainee to take the initiative and tell the attending what the treatment plan, in his/her opinion, should be.
A lot of people have said good things about Presbyterian and Methodist as well. Presby is a more private hospital which skews your patient population away from indigent care, whereas Methodist has a patient population much more similar to Parkland (a lot of indigent pt. who come in at the later stages of their disease process). I think both would set you up pretty well for fellowships as well, but I think to be competitive for GI or Cards you'd need to be at a more recognized (from a name standpoint) place.
St. Paul's has been purchased by UTSW, but they are more than a few years off from merging their IM programs with the ones at Parkland. From what I understand, St. Paul's is pretty weak all around -- attending and resident-wise.
Hope this helps.