The 083, 087, and 091 award offer what some might consider to be "1:1 conversion" to air miles. For example, for 250K MR points, you get 1 week at a Cat6 hotel + 120K air miles.

Does a week in a Cat6 Marriott sound interesting to you? Do you consider it to be worth 130,000 points? (Marriott does.) If so, then there you go - you can turn about HALF of your MR points into FF miles at 1:1, and stay in hotels with the rest of your points.

(Same concept holds true if you like Cat5 or Cat7 hotels. There's another thread on here about redepositing the hotel portion of these package awards. You can do this and get more FF miles, but you lose value as Marriott takes a chunk when you redeposit.)