I think "Spring Street" would make an excellent single -- it's become my favorite song on the album and I think it follows the general formula for a song that would do well on the radio because it has that familiar chorus. Regardless of how you feel about all the "na na na" 's (doesn't bother me, personally), you can't say it's any worse than all the "it's alright" 's in Bon Jovi's "Who Says You Can't Go Home?", and that was a HUGE radio hit.
Beyond that, I like the way she tells a story, from setting out on her own to coming of age and eventually starting her own family, bringing things full circle. The final bit about walking her daughter down to Spring Street and holding hands, yeah it's sappy and sentimental, but it's very effective the way she sings it. I could see this song becoming quite popular among people who aren't aware Vanessa's done anything since "A Thousand Miles" and winning her over some new fans.
If not "Spring Street," then I think the title track, "Heroes and Thieves," or "Hands On Me" would make good singles.
While I love "Home," I'm not sure how it would do on the radio. I'm not sure it's a single. It's a truly lovely song, though, I think it would make an excellent wedding song.