Help! Trip in January or March w/ free dining?

[AZDisney2011]

My family of 6 planned a trip for January 2-9 with the hopes of free dining - of course we are before FD starts, so I scheduled March 10-18 w/ free dining. My question is when should I go? I know March will be busy w/ spring break, but January is during Marathon weekend. Could some of you who are familiar w/ crowds please help me out? This is a once in a lifetime trip for us since we are traveling from Arizona. The cost is nearly the same for both trips, so that is not a factor. I just want the best trip where we can do the most.

Thanks so much!

Me, DH, DD12y, DS10y, DS6y, DS2y