So I was looking for a hotel award in Paris at the end of August, and Ren Vendome had a standard reward available on the day I was interested in. Logged in, chose my room type, looked at the pre-confirmation screen... but before I entered my credit card details and confirmed it, I thought "Nah, how about I change the dates and try the next day instead?"

Alas, there was no availability (even StayAnytime) the next day, so I cycled back to the previous day... and whomp, the standard reward was gone, only StayAnytimes left. I went back to the main page, tried again, same result. Log out, log back in, try again, same result. I tried going back to the original reservation session from the browser history, but nope, that was gone too. In fact, "Show Alternate Availability" showed me that standard rewards were only available on one single day during 4 weeks of Aug-Sept (which was, of course, the same day when I have a confirmed evening engagement in another country 2000 miles away).

"Hmm", I thought, logged out and did something else for a few hours. Then I tried my luck once more... and lo and behold, the standard reward was back. Not wanting to push my luck, I booked it immediately and got it too. Out of curiosity, I checked again today just as I was typing this, and the week with the day I booked is now 'awarded out' but there's a Friday night the previous week that most definitely wasn't there under 24 hours earlier.

It thus looks like just looking at reservations is enough to trigger locks on inventory; the locks aren't tied to your session; and that the locks aren't specific to the day but seem to cover longer periods. Moral of the story: if an award you were looking at seems to disappear into thin air and nearby dates all seem full, it may be worth waiting an hour and two and checking again before tearing your hair out in despair...

You've discovered the hole in the space-time continuum.

Now we have to kill you.

More likely, you saw what happened when people book and cancel rooms at a hotel. Most hotels have a certain number of rooms available for award stays (or lower rates). If people cancel their reservations, the award stays or lower rates become available. If the inventory is limited (i.e. the hotel is almost sold out), then your experience is common.

Actually I discovered this same situation when booking a room at a RI for an employee of mine. We couldn't get him in the Marriott so we booked him in the RI. The rates came up and I clicked on Reserve this Room button. Then I decided to check elsewhere, came back and the room was no longer available. After about an hour it was available again.

By clicking on Reserve this Room I think that Marriott's reservation application holds that room for a set period of time so others can't come in and book it out from under you while you complete your booking; whether your delay is due to contemplating your decision, checking air fares, booking airfares at the same time, etc. This is actually a nice feature. I hate web sites that after you have gone through all the steps they come up at the very end and say that room is no longer available.

Normally when situations like this happen there are additional rooms available for the same price or award availability so we never notice this phenomenon. However, when it is the last one available, we occasionally do. This is also a nice "feature" in that when it does happen you know that this is the last room available at that rate.

Now, it does sound like their TBR system could use some tweaks with respect to if you are in the same session then by going back and changing dates for the same property, the previous hold should be released. Now this is probably NOT a simple change and their current implementation works well the vast majority of the time because there are other rooms available. The cost/benefit ratio probably doesn�t support the effort involved.

Esp. in Chicago, it is common for let's say the 13th for 2 nights and the 15th for 2nights 2B unavailable, while the 13th for 4 nights IS available! Often they don't want to give Tue. only but in Tue. out Fri. or Sat. is fine.