This assuming you'll have a houseboat (with smaller boat), but it may somewhat apply regardless. A great first time trip for four nights (in my opinion) is the area from Rock Creek to Forbidding Canyon. Anchor in Friendship or even Dungeon. Spend a 1/2 to full day exploring Rock Creek in detail. Plenty of arches, caves, and scenery. Some good fishing too. Of course visit Forbidding to see Rainbow Bridge. In between your camp in friendship/Dungeon and Forbidding are many excellent canyons to explore and Dangling Rope Marina to refuel and resupply. I would recommend Wetherill and Cathedral Canyons for sure. 5 days isn't much, but this is doable and a great area.