Yes, it's the BU Bridge - that Montford St, over the Mass Pike, left on Comm Ave, right over the bridge stretch where a lot of people get right up on the sidewalk. And you're right, there are a lot of other bikes there, so it's not out of the ordinary to see bikes (as a driver) and watch for them.

I'm thinking that option 1 is probably better given that, mile for mile, it's less time dealing with cars.