Off the top of my head:
There are a few decent Vietnamese restaurants in Chinatown, but nothing like you get in Houston or LA. I’d check the Zagat’s for names (they all have “Pho” in them and I get them mixed up).
If you’ve never tried Ethiopian, I’d recommend that, if the idea of eating Indian(ish) food with spongey bread instead of utensils doesn’t bother you. Try Meskerem at 468 East 49th (between 9th and 10th). Closer to Chinatown is Ghenet, 284 Mulberry south of Houston, another good Ethio choice. I haven’t eaten there in a while, but there’s a decent Senegalese place in midtown called Africa (on West 53rd between 8th and 9th). I always like to take out-of-towners to the Eastern European places in the East Village, like Veselka or Kiev, unless a trip to Brighton Beach is in order.
If you really feel like an adventure, try Jackson Heights in Queens. Great South Indian food and probably a million other things. You could do a whole Queens things and go see the enormous city panorama at the Queens Museum and just generally enjoy the loveliness of the 7 train. Too bad the Mets aren’t playing yet, you could throw that in, too. Except it would be a rainout.
Robert Sietsema writes about cheap ethnic food for the Village Voice. For an idea of what’s out there, check out his columns on the 100 best deals in Latin and Asian eats in the 5 boroughs.
Possibly the best pizza in the city is Grimaldi’s, under the Brooklyn Bridge at 19 Old Fulton Street. You can walk across the bridge (maybe not so nice this weekend, but it might be fun) and then ask for directions. Bring cash. You know, my roots are in Brooklyn, but I can’t really think of anything in the parts of the borough near Manhattan that are going to be great to do on a rainy day. BAM often has interesting movies. Sorry I’m drawing a blank.
Maybe my favorite restaurant in the city is Shopsin’s in the village. Google the name (and the New Yorker article by Calvin Trillin) to see if this is your kind of place. Turn off your cellphone or Kenny will throw your ass out.
For non-food stuff, I love the Circle Line trip around the whole island, which takes about 3 hours; but again, maybe not such a great weekend for that. If it was supposed to be a beautiful weekend I’d say devote several hours to just walking around Central Park, which is endlessly facscinating, even without the orange shower curtains.
This is kind of obscure, and may get you into a part of the city you haven’t visited: theMorris-Jumel mansion is the oldest house in Manhattan, a beautiful old Colonial structure stuck in the middle of Harlem. The surrounding historic district is pretty interesting, and you need not fear walking around that part of Harlem in the middle of the day. There’s also a smattering of African and Latin restaurants in the area.
Hope this helps.