First, you made a big mistake in turning down FB because "you would be one level lower." I know those levels seem like a big deal when you're working for those promotions, but ultimately, they really don't matter. The only things that really matter: how much are they paying you, what will you be working on, and how is it going to affect your future career prospects. From a salary perspective, I'm sure FB would have offered you more, if nothing else, purely through additional leverage for negotiating. From a career perspective, having the Facebook brand on your resume, and the contacts you'll make there, would have helped your future prospects immensely. Compared to these benefits, being "one level lower" is pretty meaningless.
Second, given that you're someone smart/accomplished enough to get an offer from FB, and have 10 years of SW experience, 170k seems low. Check out the other HN threads about salaries at top software companies. Plenty of people with similar or less qualifications report total comps of 250k. That's the level of comp you should realistically be shooting for.
Third, even if 170k is "lower than you deserve", that's irrelevant. The only question worth asking is whether 170k is better than your next best option. Go find a cost-of-living calculator and you can easily figure out whether 170k in Seattle beats your current salary-location. In an ideal world, they will give you 3 months to make a decision, and during this time, you can go interview with all the other major companies, in order to find a better offer. Realistically, since you've already turned down FB and the other companies will have long interview timelines, you don't have the time for this. If the 170k offer is better than your current situation, just accept it, and you can then reevaluate your situation 2 years from now.