The 250r is lighter and easier to handle, and would be better on very twisty roads. The gs500 is more powerful (but still not a 'hot' bike) and would be more stable and comfortable at speed or on a long ride.
But these are both relatively small bikes. Either should be no problem for you to handle at your size and weight. The 250 might feel a little cramped if you sat on it.
I would say the 500, because the added power will more than make up for the added weight. It wont' make a lot of difference in your commute to school, but if you're like most of us you will find yourself going on long rides on the weekends, enjoying WV's mountain roads and beautiful scenery, and a little extra oomph will help there.
Both are very good bikes, BTW, and would suit your purposes.