Columbus Bakery is a nice spot, and if you're up for a walk, head down to Cafe Ronda in the low 70s for an excellent Cuban Sandwich. I am also a fan of Lenny's - a little pricy, but consistently one of the best deli sandwiches around.
You might give Broadway Delights deli a try (B'way 75th/76th). I have them deliver sandwiches/salads -- so I can't vouch for eating on premises, but I've always been quite delighted with what I get. Love the chicken salad!