Hey Lori,
I was in your shoes not too long ago (I will start vet school in the fall- yea!). I thought I would do a formal post bacc, but with work I ended up doing a more ala carte system. From my research it seems that any one would be fine since you need the same classes as the pre meds with some additions. I would definitely say that it's really important to know the pre requisites of the schools you are targetting, so you can be sure not to miss any classes and then come up with a plan, especially since a lot of advisors geared toward premeds won't be as familiar with these.
It would also help if you were near a vet school to take undergrad classes there. A friend did a post bacc at penn and was able to use the advisors at the vet school there ( a big bonus!). If you can find a post bacc geared toward vet that's great, but I don't think it's strictly necessary as long as you do your homework by checking the individual school requirements. I would just find a place that was convienant and that made personal and financial sense for you.
The Vet forum here also has friendly folks with LOTS of experience in the Vet application process.
Good Luck!