Only catch with airlines is that to get any kind of reasonable rate of return you need to get up into the 250,000 point range (the Cat 5 Travel Package). It's difficult to get that high without a lot of hotel activity. The MR Visa is very weak outside the hotels and there aren't a lot of good transfer-in opportunities for Marriott points.

At 60k, look for a Cat 3 five-nighter. Maybe pick up the Marriott CC with a good signup bonus and you'll go over 100k and open up Cat 5. Got any Asian cities you've always been interested in? Lots of good midcategory (but full-service) Marriott hotels in Asia... Middle East might be another area - we did a 5-nighter at the Marriott in Cairo and thought it was a very good hotel and good value for the points considering what the paid rates at all of the big Western hotels in Cairo were for our dates.