The basic premise of the question is wrong: a student admitted at UT and Northwestern isn’t likely to get a higher GPA at UT.
If you’re competitive for Plan II or one of the other Honors programs at UT, take avantage of it.
If you want small classes, apply to LACs - Pomona, Whitman, Carleton, St Olaf, St Lawrence, Skidmore, Grinnell, Earlham, Dickinson, Denison, Davidson, depending on your personality and your best fit and NPC results.
Texas medical schools are relatively inexpensive and therefore desirable, so if you are a Texas resident, going to undergraduate school in Texas will make it much easier to get to interviews at Texas medical schools than going to a distant undergraduate school.
Based on the number of lab sections associated with lectures in courses like general and organic chemistry in http://www.registrar.northwestern.edu/registration/class_schedule/4640/fall2016_class_schedule_rev01.pdf , it is not necessarily true that class sizes will be small at Northwestern.
Honestly, I’ve just heard that from people and assumed it to be true, but I guess in reality they’re both equally demanding. Thanks!
@Erin’s Dad
The average GPA for all Reed students in 2014–15 was 3.15 on a 4.00 scale, increasing by less than 0.15 of a grade point in the past 30 years. For the 2010 through 2014 medical school acceptance cycles, 89 Reed students or alumni applied to medical schools and 62 of them were successful.