Some vacations the book pays for itself, others not. Couldn't use a single coupon in Hawaii, so a real bust there. Is the So. CA one worth it for a week out there, 3 nights at DL and 4 night at Newport Beach?
If you're purchasing the book for hotel & rental discounts, than I suggest you purchase the book in your own city. That way you can take advantage of the rest of the coupons all year long.
Check out entertainment.com. You can usually view sample coupons for each city.
I don't buy a book local to the places I visit, I only buy my local book at home. The hotel discounts I get when traveling more than pay for the book. Sometimes I am able to get coupons online for the areas I'm visiting.
I guess it depends on what you hoping to get discounts on. I think you can browse the book online to see if there are any discounts in a particular area.