There's the obvious tourist stuff that's well worth doing - Central Park, the Empire State Building, that sort of thing.
The Circle Line Ferry is worth a trip as well as you get a great view of Manhattan island from the water and I also really enjoyed walking along The Highline, which is a disused elevated rail line that's been converted into an urban park.
In terms of restaurants and bars, you are pretty much spoilt for choice. If you want something a bit different though, Ellen's Stardust Diner on Times Square is worth a visit. The food's decent but unspectacular diner fayre but the waiting staff are all aspiring Broadway singers who burst into song at varying intervals. It's as cheesy as hell but quite good fun!
We liked this bar in Bell's Kitchen too:
https://www.nybeercompany.com
