The Sand Island to Mexican Hat reach can be done in one long day, or with a single camp. It's nice, with low-to-medium walls, riverside ruins, etc.
Mexican Hat to Clay Hills is about 5+ days at low water with deeper canyons and lots of great sidecanyon hikes and scrambles. Definitely the cream.
At low water, light loads are smart, since silt and braided channels can be a problem the last day or two. Having small boats to scout ahead (and enough hands to drag a stuck gear boat) is a help. Making your last camp close to the takeout (and starting early) is also a good idea.