I'm self-employed and thus see the cost of business stays go directly out of my bottom line, so YMMV if someone else is paying for your business trips. However, for me, nothing makes me pull the trigger faster on the free night guarantee than a rude employee. WHY DIDN'T THE HOTEL CALL YOU AHEAD OF TIME? They should have proactively called and said "uh, we messed up. Do you still want to come?" What if it had been your twenty-fifth wedding anniversary? I even once, on a reward stay, asked for my points back, and this was several weeks after the stay, because the hotel billed me instead of Hhonors for the room and then the desk clerk was rude to me when I called to clear up the matter.

If I were you, I would get the one free night by invoking the guarantee and then go eat at that restaurant anyway (if it was in fact a part of your trip you were looking foward to) and if the bill comes to around $55, you will have ended up getting what you were expecting at the price you were expecting to pay.