First, I'd use points for Frankfurt, rather than DC. The Frankfurt hotel is ~$100 and can be had for 15,000 points, while the DC hotel is ~$87 and will cost 20,000 points. Neither one of those is a particularly great use of points, though.

What status do you have with Marriott? Some of those redemption rates are low enough that you may be better off redeeming 135,000 points for $1,000 in Marriott Cheques and paying that way.