My suggestion to you is Pittsburgh.
It's a beautiful city.
1) The bus system is great for people without their own transportation.
There is also a train that you can take.
2)Crime is moderate, but really it's everywhere. :/
3)Cost of living is VERY reasonable. At $500-$600 a month you can find a really nice and big place.
I paid $520, everything included, and it was an awesome apartment and only 7 min. to the city.
4)Nightlife is great. Bars close at 2 am and you have your choice of Clubs on one side of the city and regular hang-out bars on the other.
5)Baseball-Pirates-sorry they suck
NHL-Penguins-sorry they suck
But you always have the Steelers-it's a really big football town, so that's cool if you like football.
6) College campuses-Pitt, Duquesne are the big ones and you have TONS of others to choose from.