Mongo is cool, and Mongoose (node ORM-like wrapper) is pretty nice as well, but after using it for a few months on a project I was building I realized that I was duplicating a ton of data. Until mongo solves the issue of joins (something that is better suited to a sql solution), I just had to revert and ended up used node-mysql which is a pretty decent node mysql driver. I was considering using mongo for sessions (with connect-mongo), but ended up going with redis as it's pretty solid solution (and according to some benchmarks, faster).
I feel you - I recently started a node project on LevelDB and ultimately switched over to an SQL database. The difference though is I went for Postgres 9.3, which has incredible native JSON support, allowing you to slice parts of your JSON data out as a record set, join them against tables, as well as other crazy things like partial indexes on deeply nested JSON values which may or may not be present.
I really think Pg is starting to blow Mongo out of the water.
Any suggestions on ORMs or npm packages to use with pg and node?
For this, check out the fantastic node-postgres adapter from brianc as well as his node-sql package for authoring SQL statements.
https://github.com/brianc/node-postgres\nhttps://github.com/brianc/node-sql