From what I have read, Georgetown really impresses me. Good location, okay name recongition, and good research program. But its also expensive to live in DC and tuition is a bit high.
I heard Madison is more like a college town atmosphere, which I know I will enjoy. I didn't apply there, but after hearing so many other people praise it, I wish I was a WI resident and have even a remote chance of going there.
Sorry, not much of a comparison, but definitely both good schools. Depends if you want the metropolitan city life, or the college town feel. From what I hear, everyone in DC is young, except for the politicians.