It sounds like you are launching from potash. It so the Bellknap's guide shows a couple a ruins that you will probally pass on day 2 on river left, but I haven't ever found them. The next hike worth doing in up and over one of the meanders. The hikers will make it up and over long before the boats get arround. There are a few glifs on the way back down to the river on some large boulders. Next and most spectacular is the Doll's House hike. This time of year you will probally want to camp in the sun wich makes the camp at brown betty a good choice. Lower spanish bottom is also a great choice and may even be better if it is windy due to the large cotton wood trees. The hike as a couple of options. It would be ideal to plan a layover day at one of the camps to allow enough time for everyone to do the hike. It is a bit of a grunt to get up to the rim. It's about 1200 vertical feet and the trail is verry steep. If you have a group of motivated people it is possible to go up and down the main trail and do the loop hike in the Doll's House in the afternoon if you get in to camp at a reasonable time, but I would definatly take lights and plan on being late for dinner. There is no water on the hike so carry all the liquid you want, I prefer mine in a can. If you do have time for a layover day send me a PM and I will let you in on a great advanced hike that makes a very nice loop.
Have a great time