Since moving from NYC, it's been special to go back and see all the things I missed while I was living there. Since I still don't have millions to blow, I like to do things that don't cost a whole lot of money.
The Cathedral of Saint John the Divine (just say St. John the Divine if you have to ask for directions) is the 4th largest in the world and the largest in the U.S. For such a tiny city, this church takes up a lot of space. It is beautiful inside and out and has a great sculpture in the garden dedicated to the future children of the world and the creativity the carry with them. I believe admission to the church is free (the lady just waved us in despite the sign saying "thank you for your donation of $10") and there are some signs around giving some historical and architectural information about the church. It's great to walk around in, especially when it's cold outside. The address is 1047 Amsterdam Ave, and it's on the upper west side. Take the 1 train to get there.
Right across the street is The Hungarian Pastry Shop with a great vibe. There are lots of pastries to choose from and the art is pretty cool. I like this place because it's different than your mainstream "cool" coffee shop. It's grungy in an attractive way and it has quite a European cozy feel about it. You should note that the prices are more if you want to stay (rather than grab something and go) but it's not that much more. If you need somewhere to warm up and check on email (or blog!) I recommend this place. We ordered a cinnamon roll which was very flaky and had juicy raisins. They also carry Jewish treats, like hamentashen. The address is 1030 Amsterdam Ave.
Hope you enjoy the places! Feel free to ask any questions.