And if you live there, you probably know more than I do.And as Matt R. has pointed out, cash flow is just a (small, in my opinion) portion of the calculus in a market like NYC.

A little about me: Currently instructing Calculus, transitioning to an MBA program in the fall.

@Alex Mid-town and few more Neighborhoods is almost like a twelve year old doing calculus.  

On the other hand, owner occupiers are generally in the market for 1 - 4 units only but they buy the properties to live in them so their valuation calculus is different.

If you haven't, another calculus would be to weigh keeping the marina home vs the GG one.

Now, it is an actual expense to you, but since it is figured into your cash flow calculus it becomes ordinary cost of doing business.

 Does it change your calculus if I'm the builder?

The answer requires a little calculus.6%< your return <= 33.5% = do the deal!!!

Hold up there with the Einstein maths failed story as it's completely incorrect.It's nice to believe to us chimps that he never failed maths, but a child he taught himself maths because he wasn't being taught that at school, and was teaching himself calculus in the first year he started to teach himself maths.To boil that down to "tenacity" is a stretch, the guy was an exceptional mathematician.

In Bay Area suburbs, maybe not so much, as they are usually less desire able than SFH...unless you're on university ave in palo alto or something...and than it's SF prices.  6- IMO your real calculus shoud be between 2-4 vs SFH.