I grew up in MI and have done several trips on Lake Superior, but never got all the way out to Isle Royale. I would like to go back and it is on my short list of trips I want to do. From here though, it is really a 3 day expedition to get there and a 3 day expedition to get back.
My memory is that you have a choice of a float plane (expensive) or a ferry, either a 6 hour ferry from the tip of MI or a much shorter ferry from Thunder Bay on the north. I have done ferrys on the great lakes before, I have to say I am a bit apprehensive about what a 6 hour ferry across lake superior would be like. Sure it could be nice; but it might also be a sea sick life and death nightmare in huge rolling seas and feel like a passage through the Drake crossing.
Once you are on the island (and you can get dropped on either end I believe), my impression is that the hiking and scenery is great. Lake Superior is gorgeous; cold, wild, and beautiful. Hiking end to end is the obvious choice, but there are also some loop trips.
I can't imagine rational people doing the open water crossing to IR in a kayak. I would guess that is far too dangerous. The paddlers at the canadian canoe routes forum (myccr.com) take paddling on LS very conservatively, recognizing that conditions can change very quickly and be extremely dangerous on what is really an arctic inland sea.
Should be a great trip, once you get there. Enjoy.