Well ... if you were willing to continue north from Mt Pleasant to I80 (at Iowa City), the Amana Colonies are just a hop-skip-and-a-jump from there - just north and west. Then you can continue on I80 through to DesMoines and on to your destination. Or ... take that way home just to mix things up (hubby and I rarely take the same way home - too much to see out there!).
Amana Colonies are well worth visiting. There are I think 7 different villages in a somewhat circle. The routes to each of the villages are well marked and most of the village shops have maps of the colonies. The biggest is of course Amana. The juxtaposition of the old Amish stores and shops and the large Amana (of "radar range" fame) manufacturing plant just on the edge of town is rather interesting.
Homemade meats, pastries, breads, candies, jams, preserves, etc.
Homemade brooms, a wool and cotton mill, antique shops and art galleries
Handmade knives and kitchen utensils and cookwear
And of course quilts!! Antique quilts, handmade Amish quilts, quilt shops for fabric, handmade lace
Take a look.
http://amanacolonies.com/pages/shopping.php
If I was within 70 miles (which you will be), I wouldn't miss it for the world. Plan on spending some time there though. There is a LOT to see and it's well spread out. I need to go back in fact - I haven't been there since 2001!!!