D.C.
I've heard alot about the North Hills Y as well, but to be honest, it's pretty expensive. You have to join the Y ($100+ initiation fee) plus pay monthly fees, then pay for the lessons on top of that.
North Hills School district offers lessons at a very reasonable price (around $35, I think). You've missed the fall deadlines, but they will have lessons in the spring semester too. Signups will be on Feb 3. It's not up yet, but closer to that time, they will put a flyer up on the website attached to the Feb 3 calendar - check on it early after the new year (http://www.nhsd.net/calendar_events.cfm).
North Allegheny and Shaler school distrcits probably have similar programs, but I haven't looked at theirs.
Good luck!