From the equivalent location in Boston (Beacon Hill) your a 15 minute or less Uber ride away from the gate at BOS. For flights that have dedicated security lines or if I get pre-check I'd leave downtown Boston 1 hour and 15 minutes before takeoff. I've only been bitten by this once in the last few years, in which case you can find an airline employee to get you through the security line ASAP.

However, even if you want to get to the airport early, it's not like that time is wasted. These days I would say relaxing in the airport is just as nice as relaxing in a train car: http://www.nytimes.com/2014/12/08/nyregion/improving-ground-.... The last time I was at LGA early I had a huge table to myself and the person I was with, and the table had an iPad I could use to order food and drinks.