I stayed in the airport last week for one of my runs due to a flight arriving much later than planned...why hurt the CPM for five hours of sleep?! Not the best move...Boston is a terrible airport to hunker down for the night. The chairs outside security, while nicely padded, all have chunky, intrusive armrests, which prevent laying down (unless your extra flexible perhaps). Moreover, there are security announcements and that lame music station ("...the sound of Boston Logan") playing all night.

The best place I found was in that long above-ground walkway that links terminals A and E (I'm pretty sure it's A and E...it's that longest one that takes several minutes to span). There is a stretch that is adjacent to the parking and the self-pay machines where there are several white benches. The benches are metal unfortunately, but are otherwise fine for laying flat. In this area, you cannot hear any announcements/music; there is the constant whoosh from the A/C system, and I prefer such background noise. You'll also be lonely...very few people walk through in the wee hours. Don't choose a bench too close to Terminal E, otherwise you'll hear Ted Kennedy repeatedly welcoming you to great state of Massachusetts.