If you are at MIT, then you can basically live a lot of places, but as others have pointed out you can live in posh places or student places.
Someone said Allston/Brighton - Forget there. Dumps. BU and other College Students mostly.
Back Bay - Nice area, $$-$$$, maybe okay if you get a roommate as far as cost wise. Parking tough, but doable, especially if you pay.
Cambridge - Davis/Kendall/Harvard/Porter Squares. Hit or miss, but crowded and expensive usually. Mixed crowd of college and young professional. Parking will be typically tough.
Brookline/Cooledge Corner/Longwood area - This a great place to live. Mostly young professionals. Not too outrageous for $$ if you hunt around. My wife lived there while we dated. She lived on the top floor of a 3 fl. Brownstone. 3 bdr /1 bath. Parking should be fairly easy with the right unit.
A Couple of other places to think off that would be fun, less expensive, a little quieter and good for a car.
Watertown - Good restaurants and some nightlife, but far enough from the "city" to make it more affordable and more likely to have good parking. Depending on where in Watertown, you can ride a bike to MIT in about 20 minutes or take an express bus into the city. Lots of young professionals live here
Newton (West Newton or Newtonville) - Newton has many sections, but Newtonville and West Newton have some great eats and hangouts. More room for the car and probably a lot cheaper. Commuting to work is a little more of a pain, but not unrealistic. Take the Commuter rail to South Station (~10 minutes) and then catch the Red Line to Kendall Sq (MIT) another 10 minutes.
Arlington - Great place and a mix of young professionals and families. Very easy access to MIT/Kendall Sq. from Alewife Station (Red Line). Live on the east side of Arlington and ride your bike, or take a bus, to the T station or walk and then it's a 10 minute ride to MIT. You can car park at the T station at $7/day (Cash only). Arlington will be relatively inexpensive housing and easy to park a car. If you want to go out in the city (Boston), just leave from work and and then head back to the urban burbs (Arlington, Brookline, Newton, Watertown) at the end of the night.
I live in a burb just on the other side of Rt 95/128 about 15 minutes from Boston. When I first moved here, I was single and lived in Belmont, but looked at buying a house in Arlington and Watertown. I was 28 when I moved here, so about your age now.