It's a wonderful hotel; we stayed there the weekend of our wedding and got quite a lovely treatment. (It was a points stay and we paid extra in advance to upgrade to a park view room, foregoing a potentially free (but space-available) upgrade to a partial park view room due to Marriott Gold status.
As you can imagine, nothing there is cheap. I feel like we spent over $100 on room service breakfast for two one morning, and didn't order anything outrageous.
There are tons of things to do in the area though (it IS New York!) so you don't really need to worry too much.
A few things I would recommend in the area, in no particular order:

• Jam's restaurant (especially the roast chicken), at 58th & 6th
• The food hall in the basement of The Plaza hotel
• Quality Meats and Quality Italian are both good but a little pricey (it IS New York!)
• Angelo's Coal Oven Pizza
• Rue 57
• Sarabeth's next door to the hotel for Brunch
• Lots of fast casual and sit-down places on W 55th & W 56th streets (between 5th & 6th) popular with office workers during lunch (e.g., Joe's Shanghai for soup dumplings, Naya for Lebanese)
• Black Tap Burger for pretty good burgers and instagrammable deserts (go before noon for lunch; it gets crowded). Many people like Burger Joint inside the Parker Meridien (also go early), but I'm not such a huge fan
• Souvlaki GR for cheap but good Greek