I think it’s a pretty safe neighborhood even at night, but I’m a young white male so my perception on that topic is somewhat skewed. Even so, you’ll be surrounded by other patrons leaving the theatre, and once you got off 4th street you’ll be on major avenues which will be well-lit, and probably fairly busy.
I haven’t seen Dreaming Zenzile (have tickets for later), or Romeo & Bernadette.
Might be worth looking through the digital rush options on TodayTix, and see what catches your interest. It’s not THE busiest time for Off-Broadway, but there’s a fair amount of cool stuff going on right now, and coming up in June.
I liked Islander a lot!
For Music Man, you just have to decide if you feel it’s worth it to wait in line and see Hugh Jackman and Sutton Foster. Aside from that star-power factor, there’s not much other reason to see the show unless you happen to be a big fan of The Music Man. Everyone has a different idea of whether it’s “worth it,” so no one can make the decision on your behalf.