1h 30m commute is only if you insist on busing down to Apple or Google every day. There are plenty of companies you can work for in SF that you can reach in much less time.
And if you think it's going to be affordable to live five minutes walk from your office in NYC, think again.
I agree with you on SF. There are certainly a bunch of great companies to work for there. However, at the risk of angering a lot of people, the majority of promising startups are in the South Bay.
NYC is expensive, but not unbelievably so, especially when put next to SF. To live within a 5-10m walk of Palantir's office in the West Village is roughly $4k for a 2BR(so I'll be paying $2k/month). Certainly not low rent by any stretch of the imagination, but it is definitely affordable with an engineer's salary. Also, the difference in salary compensates for this cost.
I'm not sure where you're getting your information that the majority of promising startups are in the South Bay.
The energy in Silicon Valley has been shifting northwards for the last 10 years. The majority of large companies are in the South Bay, but among companies less than 5 years old, there are as many great ones in SF as in PA/MV.
And you're right about one thing - if I ever found myself suddenly single, I would move back to NYC in a hot second. As a (somewhat) sane straight guy with a bit of money, that dating scene can't be beat. Hands down.
What you need to do if you want to live in San Francisco and work in Silicon Valley: get a (stupidly expensive!) apartment near Caltrain, take an express train down (30-45 minutes, and work on the train), then get the rest of the way to work quickly (helps if your startup is near the train - mine is ~20 minutes' ride, not the greatest).
It's probably not as good as you're getting in New York, but it's significantly better than 90 minutes.
And if you think it's going to be affordable to live five minutes walk from your office in NYC, think again.
(disclaimer: lived in both)