Watertown Square. I'm in a 2 bedroom 2 bathroom apartment with a roommate, and we each pay somewhere around $1200/month, but we're in a pretty nice building (compared to the falling down rat infested places I lived in with way too many roommates in Allston before, at least) so there's probably cheaper housing available. I'm right across the street from the 52, 57, 59, 70, 70A, 71, 502, and 504 buses.
52 - Goes from Watertown to Dedham Mall, passing through Newton Center. I think so at least - the route changes a bunch depending on the time of day and I've never actually taken it. Headways are in the 20-90 minute range, runs 7am to 7:30pm weekdays only.
57 - Goes from Watertown to Kenmore, passing through Oak Square and following the B branch of the Green Line from Packards Corner. Key bus route, 10 minute headways, runs any time the T is open including late night service.
59 - Goes from Watertown to Needham, passing through Newton Highlands. Headways around 35 minutes, 6am to 7pm weekdays and Saturday, 90 minutes 7am to 5:30pm Sunday.
70/70A - Goes from Waltham / North Waltham to Central Square (Cambridge), passing through Watertown Square and Arsenal Mall. Headways seem to have been created with a random number generator but average out to around 10 minutes (two buses a minute apart then nothing for 20 minutes, weird stuff like that). Runs most of the time the T is open but not the extended late night thing on weekends.
71 - Goes from Watertown to Harvard Square. Key bus route, headways generally 10-15 minutes, runs any time the T is open including late night service. Technically a trackless trolley.
502 - Goes from Watertown, gets on the Mass Pike and goes straight to Copley. Inner Express bus with higher fare. Headways 5 minutes in morning and 15 minutes in evening. Only runs during rush hour on weekdays.
504 - Goes from Watertown, gets on the Mass Pike and goes to Downtown Crossing, passing through Copley. When 502 bus is running, skips Copley and stays on the highway longer. Inner Express bus with higher fare. Headways 5-30 minutes depending on time of day from 6:30am to 7/8pm on weekdays, around 40 minutes Saturday.
Only nightlife I've encountered has been along the lines of a 24 hour CVS, but I don't know anything about bars and there's a ton of transit so you can always go somewhere else for stuff like that. For the most part it's pretty quiet and there's not a ton going on, but there are some stores and restaurants and stuff. Has issues with gridlock and assholes who think honking their horn continuously is going to magically make the other cars vanish, then other assholes honking back at them, then honking at the person honking at the person honking, etc. I don't have a car, but my apartment came with an off-street space my roommate uses. There's street parking but it's not allowed during the winter so a lot of buildings have driveways or lots, but the street parking ban doesn't seem to be enforced since there are still cars parked everywhere.