Cevabdzinica Sarajevo on 34th Ave. at 38th St. is a 5-minute walk away, if that. It's quick, it's casual, and it's tasty. Good sarma, burek and grilled cevapcici. Generous portions; if you get the $8-$10 meat platters, you probably won't need one per person, especially kids.
The Cuban place on Steinway near 35th is good, cheap and cheerful. We had a respectable cuban sandwich and ropa vieja plate there some time back.
The service at Cup is eager, helpful and friendly, but I wouldn't count on quick. The place is the size of an airplane hangar, there are lots of obstructed views and the waitstaff have a lot of ground to cover. You can sit there for a looong time without even seeing your server. And agreed: the food is just so-so.