I work for a company that does consulting in a specific niche to governments, national, state, local. We don't put people on-site full time because of the nature of our projects. I found that I didn't start travelling heavily until I became a project manager taking care of 2-4 current and 3-5 prospective clients at a time. Now, I am supposed to travel 40% on average but probably travel closer to 50% - enough to make second-tier elite on one airline. I travel for fun with all my vacation time, and that gets me up to top-tier.