Boston can be nice in November or not so nice. There is Indian Summer where the temps in the day can hit 70s and sunny. But at night, it can fall into the 40s, 30's or even lower. Also you can hit a stretch of cold rain coming off the Atlantic. Snow is not likely in November, but it can happen. Of course some people's idea of great weather is temps of 100F and dew point above 70. I'll take the cold and snow.
Not sure what you mean by sites. Touristee stuff like Beacon Hill and the State House are close by. The Aquarium which is closeby is world-class. You might want to check out in advance Boston magazine, especially for food and clubs. The No Name Restaurant is a good place to go for seafood. Faneuil Hall is another tourist spot, but no great shakes anymore. Typical stores you'd find anywhere else. There is a theater district downtown, so you might want to check this out in advance. Also check out if the Bruins or Celtics are at home, if you like sports and have $$$ to burn.
If you are not renting a car, you want to get a Charlie Card for riding the subway and trolleys. You can take the trolley to Coolidge Corner in Brookline, where you'll find more interesting restaurants. Downtown Boston is a great walking city, but I'd recommend being careful where you walk at night. You especially don't want to walk after dark in the Boston Commons or the Public Gardens. If you rent a car, pay close attention to parking signs and be sure to feed the meters. Boston is notorious tough for towing in the downtown. Sometimes they tow even if you are legally parked.
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