I have a couple routes you might find interesting. Note that the ferry schedule depends on the date (off season it will not run every day)
To fish Lake Superior waters you will need a Michigan fishing license, but if you only fish inland water then no license required. Read "The Greenstone", the park newspaper, for fishing regulations (
http://isleroyaleforums.com/download/Gr ... e_2012.pdf)
Route 1 (Easy miles with dayhike side trips)
day1: arrive Rock Harbor, hike -> Three Mile, dayhike Mt. Franklin, explore the east end of the Greenstone
day2: hike -> Moskey Basin, swim
day3: hike -> Chippewa Harbor, explore sunset ridge
day4: hike -> West Chickenbone, dayhike west on Greenstone to overlook
day5: hike -> McCargo Cove, explore the mines
day6: hike -> Rock Harbor, visit Ojibway firetower on the way
day7: explore the Rock Harbor area, ferry -> Copper Harbor
Route 1 includes Moskey Basin, Chippewa Harbor, and McCargo Cove, arguably three of the best campsites on the east end of the island.
There are plenty of opportunities here for day trips to cool spots, and flexibility to change your route based on the weather or how ambitious everyone in the group is feeling.
Lastly, it gives you a day at Rock Harbor, to explore Scoville Point or rent a canoe to explore Hidden Lake/Lookout Louise, or maybe rent a motor boat and cruise to the lighthouse and explore some of the outlying islands.
Route 2 (longer miles, see more of the island)
day1: arrive Rock Harbor, hike -> Moskey Basin
day2: hike -> Chippewa Harbor
day3: hike -> McCargo Cove
day4: hike -> Todd Harbor
day5: hike -> Hatchet Lake, hike -> West Chickenbone via Greenstone
day6: hike -> Lane Cove
day7: hike -> Rock harbor, ferry -> Copper Harbor
Route 2 has longer miles, but lets you see everything from route1 + Todd Harbor, Hatchet Lake, and Lane Cove. Only has a little time at Rock Harbor to explore before having to catch the ferry out.
Other interesting routes can get you further into the backcountry if you are willing pay for a water taxi, but as a first time visitor I think it will give you a better appreciation of the island to travel by foot.