It's a good question. I'm in the same situation, although I don't have nearly as many points, so I'll probably add some more Marriott points before I do anything.

Ultimately, I think you should do whatever puts the points to work on an airline or in some other way that offers value to you. Even if you take a hit, like with the 3:1 points to mileage ratio offered by Marriott, you'll be using the points in some way that is more meaningful.