I hope you're getting some kind of income from your SF property through rentals. Otherwise, you're paying TWO mortgages??? Why??
I moved to DC kind of in a rush, and re-bought all furniture, stuff, etc. So, all my stuff is still at the house in SF... I've been paying two mortgages for about a year now. It's not easy to clean out a house!
You're really getting screwed with the new tax laws regarding mortgage interest and property tax deductions capped at 10k.
I have a lot of equity in the house there, and owe only about $150K for a home worth over a million. And, my mortgage there is only $1200 per month, which is almost impossible to find nowadays in SF. So, my intention was to hold it as long as possible...
Unless you rent it out, paying $1200 on a $150k loan, the amount of accrued interest over the remaining lifetime of the loan doesn't make much financial sense. The only thing that does make sense for holding on to it is if you see the marginal value of the house exceed the amount of the loan OR you plan to move back in the not too distant future. If you don't see yourself moving back and you don't want to rent it, sell it for a profit. Use some of it pay down your current home, and invest the rest in a passive index fund where you'll likely see 9-10% growth rate in the next few years.