As for determining how big a pay cut is "worth it": I'm sure some econo-wonk can devise a formula to calculate the optimal combination of pay, perks, commute and job satisfaction. But I see this as less of a math puzzle and more of a mosaic that can be arranged any number of ways for a satisfactory outcome.
The biggest piece is salary: Will it be enough to cover the things you can't live without? Then, arrange the other pieces you're offered — vacation time, gym discounts, level of responsibility — around it. Step back, and see if you like the overall picture.
Of course, you don't want to settle for just any offer. But you're currently spending about half your life slogging to, from and through your workday. Rather than hoping to find some golden ratio to justify the leap, you might just work on solving for "why."
Karla L. Miller writes an advice column on navigating the modern workplace. Each week she will answer one or two questions from readers. Miller has written for and edited tax publications for 16 years, most recently for the accounting firm KPMG's Washington National Tax office. You can find her on Twitter, @KarlaAtWork.