@Account Closed, a lot of great information in this thread, kudos to you and to all of the people who are chiming in. Just a few things to consider:
What does it cost to actually live where you're living now, and can you live elsewhere for cheaper and be as happy as you are in your current living situation? It seems your best option is to stay put in your current unit (as long as you can afford payments and are happy there). You've mentioned a few times that this is all supplemental, since you have the means to invest elsewhere without house hacking. If that's the case, then I'd say just jump in to a different area that you've identified or are identifying, strictly as an investment, and keep living where you're living. The co-op market in NYC is softening a bit, units are staying on the market a bit longer, etc. I would not count on a co-op to cash-flow, and even if it does, I wouldn't count on it to remain cash-flow positive. You're just too much at the whim of the Board, even if you're a part of the board.
There are a few areas around NYC in which you could find multifamily properties that present value-add opportunities. For instance, I'm closing on my first property, a mixed-use 4 unit property in Yonkers. As I've mentioned in a few other threads, still a way away from really exploding, but the potential is there. And if it's cash-flowing and vacancy rates are low, then a crash won't hit it as hard.
One thing I pointed out in another thread, as well: With buildings in NY that are 6+ in most areas (in some areas it's 12+ units, 20+, 50+), the units will be subject to the Emergency Tenants Protection Act of 1974 (rent control, basically). Just something to keep in mind if you're looking for forced appreciation, as it will be much more difficult to accomplish.