That feels like a consolation prize. And it does not seem like good currency when you change jobs (especially for companies that demand current salary information).
1. It's now illegal in California for employers to ask for salary history.
2. Vacation days, if they're not unlimited, are compensation and must be paid out if you leave. That's not base salary with which you can negotiate a higher offer at another company, but it is money.
OTOH, I know of people in the company who struggle to take more than two weeks.
During my last job search I would point-blank ask the hiring manager how much PTO they and their reports took in the last year.
If you have a wedge, use it.
I'd think it would apply equally to asking for a raise, though I haven't tried it.
Make a list of nontangibles. As a reference, look up the benefits people get (by law) in countries like Sweden, France, Denmark, etc. Stuff like minimum 4-5 weeks vacation, 6 months paid medical leave when you have a kid, etc.
Then ask for one or two of them. Don't be a jerk about it. Just say it would be really important for you to have it. Mildly make it a problematic point (i.e. don't say "yes" to the offer - just keep asking).
They most likely are not going to give you them (in the US). Since these are hard to give, but not unreasonable (so many countries give them), they will not get offended. After a few back and forths, they may come to you and say "Look, I'm sorry we cannot give you X, but would you be willing to accept an increase in pay as a substitute?"
So don't ask for a salary and settle for vacation (unless that's what you really want). Ask for a lot of vacation, and settle for more money.
Instead, add a (reasonable) raise to your current salary, then add another X percentage just in case you don't get a raise for a couple years. Hand the hiring company that figure.
Edit for clarity