My experience in floating "The Canyon" has been multi day trips, at least 8-9 days. There are some shorter, day type trips but access to the canyon is very limited.

My friend operates Grand Canyon Expeditions, www.gcex.com. They operate dory & raft trips. Due to the limited time I can take off from work, I have only gone on the rafts. I would love a dory trip but they are typically two weeks. It is a great trip and you do spend a lot of time exploring the side canyons. The put in is at Lee's Ferry, near Page. The take out is either Diamond Creek or a jet boat trip to Pierce's Ferry on Lake Mead.