Allison, carefully consider your needs before swapping in the 172 for something else. You say you commute weekly from home to med school. I'm sort of assuming that you have no desire for a commercial flying career, but you're flying now because of the commute. In that case get a commuter airplane: one that's simple to operate, simple to maintain and has a high reliability record. The 172 can probably repaired with just a hammer, some duck tape and a leatherman, and spare parts abound. That's what you need right now.
If you're looking for something more flashy because you think that goes well with your age, let me tell you that most of your friends probably think you're cool enough already for owning a plane and knowing how to fly it. And your 100 knots is a lot faster than what they can legally do on the highway in their flashy cars anyway.
A commute is a commute... It's a drag no matter how long it takes. But it's worse when you can't commute because your mode of transport is down and you're waiting for spare parts to arrive from some volunteer owners club half a country away. One day of downtime at the wrong moment costs much, much more time than shaving five minutes off a commute each week.