Hey, I was on a j1 for the summer '08 in Boston, it was unreal! Most of us got jobs there, we were living in Allston, outside the city. We headed to Nantucket for the first week, had a house there n all but it was way too expensive n we cudnt get jobs! So id go near the city if I was ye, theres a public pool on the way to Boston College anyway I think, n u can always get a T to the beach. I wudnt head to NY on a j1 coz ive been there twice now n its ridiculously expensive, duno how anyone cud do a j1 there, not in the city anyway! Have heard Chicago's very good aswell tho, but I reckon the weather wud b better in Boston! Good luck with the decision-making!
big city living in a suburban area. many different districts all with different cultures and feels to them. every where you go is like a new country. and all within a 20 minute commute for no more than $2. basically san francisco has everything for every one. there is also berkely across the bay with loads of frat houses and co-ops and is also an easy commute to the city for work. plenty of summer jobs available as san francisco has the highest influx of tourism during the summer than any other city in the whole of the US. weather is not roasting but you can get a tan. and again if you go to different districts you get different climates. mission generally the warmest. you can chill out in dolores park have a beer and a smoke and flake in the sun.
also with san francisco you are no more than a QUALITY 5 hour roadtrip south to san diego, LA ,vegas, Santa barbara, or north to seattle, lake tahoe. nothing better than cruising down highway 1 along the coast in the sun in a ford mustang or dodge charger, easily and cheaply rented in sf. bout 200 bucks for a week.
i spent the summer there last year and will be moving back over in a few weeks for a year. this place has everything. its a culture vultures dream. or just a great place to party. or to shop. or to chill out. or to basically do whatever you want.