Muck/cement boots. They will be your best friends for several reasons: after you get out of your paddling gear you can walk out to the boats without getting your feet wet (you will do this a lot), they keep the sand out and they are generally quite warm. March nights are cool to cold and wet feet are less than ideal. Also shoes at night go a long to to prevent cracked and bleeding feet. The overboot style works well, if you go with the standard type make sure that they fit well - a girl on my trip got blisters from a poor fit on hers - but they were pink so she got style points. They also make peeing in the river easier for girls as they can be standing in shallow water when they squat instead of trying to stand on dry land while peeing into the river. Of course a pee bucket can also take care of this issue.
I have a GMER drysuit, it rocks, not parting with it anytime in the foreseeable future though. Anybody I know that has the semi-dry SuperNova paddling suit says that they are a great option at a much lower price point. As long as the neoprene neck gasket fits you properly it is essentially dry. And for under $400 it is way more economical. (The Kayak Centre | Kokatat SuperNova Paddling Suit