Having stayed at the Berlin Marriott just last month and over a weekend at that, be prepared to be Totally Lied to about them not having an available room w/o paying for the night.

They have there own set of T&Cs when it comes to dealing with things even thou Im a Plat. Was denied all Upgrades even thou I went up to the Lounge (nice indeed) and had to argue to get access for that too, and printed out that they had all sorts of better rooms for Sale and keep being told we were completely sold out. I checked in at 4pm was at the Hyatt the previous night. Getting a late check out was a bit easier as I keep remiding them how they hosed me on not upgrading me, but when asked at first w/o mentioning the hassles with Upgrading and the Lounge, they werent so forthcoming

Its a very nice Hotel and great Location but then that can be said for most Hotels in that area.

As for PLing another Hotel or using pts for a free night. Be prepared to be told Checkout is at 11am or noon. The fact that you didnt check-in till 10am really wont be worth much. So if it was Me Id do 1 of the following as others have suggested ante up the extra $$$ and book The Marriott for the night you are flying in or play the Game and hope you can check-in at 10am. I would play the game, heck the Brandenburg Gate is only a 5 min walk as a few mins more is the Reichstag, as well as the new Holocaust Memorial. Or walk over to the Topography or terror exhibit and almost a complete block of the old Berlin Wall that still remains. Or if its a beautiful and warm day walk into Berlins Central Park 2 min walk and catch some rays. The Hotel will hold on to your bags till you get back and check-in.