The company that I work for rolled out an internet booking system through ITN last year. It gives you all of the preferred airlines, hotels and car rentals (read discounts). If you do not choose the cheapest choice, within reason($800 vs $200), it will ask you to choose one a reason from five or so choices to explain why, however it will not block the choice. Additionally they do not mind if you use it for personal travel, since it helps out the discounts, etc.