I'm probably biased but I don't know of anywone who uses yellow pages anymore, especially for travel. The local yellow pages, at best, will show me hotels in my local area. Unfortunately, when I need a hotel, it's not in my area!

I would transfer your yellow page advertising over to more online marketing, specifically PPC. Even if you are already doing strong web marketing, there is always room to improve.

You don't have to do it all at once, you can slowly (over the course of a few years, perhaps) reduce your Yellow page spend. Keep good track of the effect. If you see a significant impact on bookings, investigate and make sure that's due to Yellow Page advertising and not something else.

My bet is you can eliminate Yellow Pages and never notice the difference.