Over-looked, but fascinating
I went to the Medici-Riccardi palace last summer, and I thoroughly enjoyed it. It's one of those fascinating places off the beaten track, even though it's right on it.
What's there?
-Benozzo Gozzoli's The Procession of the Magi painting in the Medici chapel. A wonderful testament to the family's wealth, power, and good PR skills. I just kept going back there...
-The modern Tuscan government's headquarters. Check out modern Italian government and think of how funny it is that their building was a center of the "Godfathers of the Rainassance." The people there are very nice and friendly
-I believe the Medici libraries are there.
-The courtyards of Lorenzo de'Medici, and other pivotal birthplaces of the Renaissance. Just sitting there and imagining all of the artists and other historical figures that came here to exchange ideas and sculpt western history should be reason enough.
I have to warn, though...because the Medici family moved out of this house, it has changed ownership, and many of the artwork formerly in it has been moved into museums, don't come here expecting there to be HUGE exhibits (although there usually are some. At least when I was there, there was an exhibit on ancient Greek and Roman sculptures, possibly some collected by the family).
In conclusion: There isn't as much here as in other places in Florence, but what IS there is very, very amazing and well worth it.