I keep seeing this term pop up while I'm looking for hotels, I've never heard of it before. Any help would be appreciated. Thanks!

I believe it means you can have any room in the hotel for that price (assuming the room is available, of course).

My personal experience with this is that (twice) I got the worst room in the hotel

Cynically speaking, it means that you are paying a flat rate and could end up with any room in the hotel.

The optimistic interpretation is that you get the best room available at the time (although I can't imagine you'd end up with the Presidential Suite if it were available).

The pessimistic interpretation is that you can't specify the room type - e.g. you might get two twins, you might get one double bed, maybe smoking, maybe non-smoking.

I've never done it - anyone ever get the Presidential Suite? I might try my luck next time!

"Best available upon checkin"
Could be anywhere, any type.

I am not sufficiently sure about this, but I think that OReilly's experience is closer to accurate.

I think it means a "full" rate which carries none of the restrictions of a discounted rate, but is less than "rack rate" - - because it does mean that they can choose the room to give you, and you agree to that (because you do at least have a room for sure, at a fully refundable rate). I don't think it is used by individuals so much, more applicable to groups or convention boookings?

Best wishes,

Rex

You get whatever's going, i.e. the 'chef's special of the day' only as it applies to a hotel room, not a dish. It's usually cheaper because as others have already pointed out, you're taking pot luck as opposed to ordering your room a la carte (this or that bedding arrangement, this or that view, etc.) Note that the hotel must still accomodate the specified number of people (i.e. you won't get a single if you requested an ROH double, etc. etc.)

"Run of the house" means the room you get is the choice of the hotel at the time you check in. It does not refer to the rate (sorry, Rex) and can be associated with anything from rack to deeply discounted. It is gamble - if you hit it off with the desk clerk and they have a nice room open you may get it, but you have no guarantee beyond what it states on your reservaation - e.g., "room for two, run of the house" can be anything that will accommodate two people, from the worst broom closet size room behind an elevator to an executive level suite. If you have frequent guest status with the hotel company you are less likely to get a lousy room.