Drivers aren't so good in the Boston area -in fact Boston drivers are notorious for how bad they are even in other parts of the States. There are really two big advantages to cycle commuting over here: i. the roads are wider (makes things easier) and ii. drivers, on the whole are slower.
However, the bad: i. if you are on a narrow road, drivers can be astonishingly bad at figuring out if they can get by, ii. a *lot* of people drink and drive, and iii. even though they are slower, culturally people tend to pay much less attention, and there is an attitude that driving a vehicle is a divine right (one that certainly doesn't need focus or concentration).
While I'm really looking forward to getting back on the bike to commute, I don't like cycling home past 3:30pm at this time because of the loss of daylight and inattentiveness -people at that time just want to get home. Add in poorer road conditions with snow or ice, and I'm in no hurry to get on the bike (or buy the Nokians like Bentmikey suggested!). If I do commute, I'll be leaving work early until we get a bit more daylight. My worst fear is that one day I'll be nailed from behind by a big SUV driven by someone chatting on their phone, drinking coffee and flipping through a magazine (and yes, I've seen that). But if you think like that, you'll never do anything....
It's kind of six of one and half a dozen of the other comparing drivers over here to drivers in the UK*; overall, I think I prefer UK drivers as I feel driving is taken more seriously (though like anywhere, you'll always get drivers who don't pay attention). However, my commute in a morning is very very quiet -I guess much depends on your commute as well.
I used to run at lunchtimes on the Battle Trail in Lexington -it's where the British soldiers (marching in bright red uniforms with big white "aim here" crosses on) were shot at and harassed by the colonialists. There are a few places where there are graves of British soldiers -which is a bit sobering and sad at the same time. I'll probably be running on the trail again this year.
*caveat: I left the UK 20 years ago, and while I visit whenever I can, it could be my perception of UK drivers is outdated
How are the drivers in New England? I usually travelled in cabs or friends' cars, only once getting a chance to rent a car and never cycling out there. It seemed to be a lot more "English" in its attitude to road use and users than, for instance, California where one would think they sold the rights to the tarmac to the bidder with the largest SUV.
My commute is currently a fairly lumpy 10 miles, which is pretty good. The last place I worked was a flat 8 miles which was 30 minutes and I often went out for a run after work as well.
I've just realised, I'm currently wearing my "Life Free Or Die" t-shirt.