Macinack Island is so beautiful - I'd much rather stay on the island and get a better "feel" for the relaxed tempo of the place, during the day during ferry runs, it is a tourist place - the main street - it is so quaint due to no cars - the fort is a fun place for kids to hang, to do a buggy tour is fun!!
For families I do reccommend Mission Point, its close enough to walk, they do have bikes there, they may not be in the best shape, but for guests its an ok way to go!! They have a pool there, and good eats!!! We've not been in awhile (we honeymooned there, took family vacations - just love it!!) There is the golf course by the Grand Hotel - and one more isolated, constructed in the Scottish Style (think rough roughs!! ) there used to be a wonderful butterfly "garden'/museum that was awesome - go to the tourist board - place - store- they will list special attractions - my favorite is movie night at Mission Point!!
We stay in the condominiums back by some resort way west of downtown,
do take a walk around the island - its only 9 miles - take a picnic lunch - find ways away from the crowds during the day, hire the horse rides - go on the trails again, you will fall in love with the smallest things!!