Most business travelers have little or no choice in who they will fly, since travel decisions are dictated by corporate travel policy and administered by online or call-center travel sources. My employer has contracts with a limited number of airlines, including CO, AA, UA and DL. Where airlines do have codeshares, e.g. NW/DL/CO, AA/AS, UA/US, I am permitted to travel on the other airlines as long as the ticket is issued on the contracted carrier. Same goes with hotel rooms, as our contracts are with Marriott and Hilton. I can get exceptions to travel policy, but it is a nightmare to do so. Car rental is either Hertz or Avis.

Personal travel is my choice, but business travel terms are dictated to me and I must follow.