Any suggestions? Have 6000 Points
I'd suggest looking at the games list here. If you see any that interest you, see if you can get them elsewhere, like Amazon, Best Buy or NewEgg. Physical copies will still work after today, but the digital downloads won't be available to buy. The key thing is to look at games that are download only, cheaper as digital versions, or games that have DLC that seem interesting, as they'll go away today. If you can get the physical copy for a decent price, save your points and buy the physical (now or later...if it's available) version.
That's why jdawgg is mentioning Gears of War. It's cheaper to download than it is to get physical copies. But sometimes a seller drops their price. Unfortunately, after today, supply and demand will allow the physical copies to go up in price. But places like NewEgg or Amazon may keep their standard price, so it's better to use your points on other stuff, especially digital things that are going away.
Some DLC for Microsoft Flight is free and some is paid for. The paid for adds more to the game. Gears of War PC adds an extra few chapters to Act 5. Their not as fluid as the rest of the game, as they were designed by People Can Fly, using some planning from Epic that was dropped due to time constraints to get the game out back in 2006. The PC version has the cooperative play and online multiplayer.
Most of the games I own for Windows Live I also have for the 360, and they tend to play the same (especially because I use a wired 360 controller to play). It seems like most of the games that have DLC are full retail games, except for Microsoft Flight and Game Room. I'd look at that list first, see if you have yet to play any or have interest in them, and then look at the DLC. Especially if it's free, get it and then look at the prices of the digital and physical game and decide which is the better use of your points.
As an example:
Batman: Arkham Asylum is $50 for the digital download. I was able to get the Arkham Asylum Game of the Year version from Amazon for less than $5. It was on sale, and was a digital copy through Amazon, but it was much, much cheaper than the Xbox.com price. Plus, the Game of the Year version came with the extra DLC.
Unfortunately, Arkham City's DLC never went on sale for Windows Live. It'd be cheaper to buy the Game of the Year version of that, digitally from Steam or another place, than to buy the game and all of the DLC for it.