I was not allowed to use Priceline to bid and pay for hotels, even though it would often save $100/night on guaranteed trips. I gave up the fight and now reap the affinity program benefits anyway. Although my current employer would definitely allow this. I make a point of inquiring about travel policies during the interview/offer phase, to make sure their travel policy is going to be amenable to me being on the road 20-30 weeks per year.