Stores with good kayaks and gear in stock and polite, knowledgeable staff.
Cartwright & Danewell (Grayling) - Great selection, worth the drive from anywhere in the state. We've bought several boats here and couldn't have been happier with the service. Cartwright and Danewell sells Dagger, Perception, Current Designs, and Necky.
Moosejaw Mountaineering (Grosse Pointe) - While all four Moosejaw stores have a selection of high-end outdoor gear, kayakers should head straight to the Grosse Pointe store. The staff is friendly and knows their stuff, we found them very accommodating in setting up a test paddle that met our schedule. We bought a Dagger here, they also carry Looksha and Current Designs.
Canoesport (Ann Arbor) - Great stock, even have a number of boats to see in the winter, including Perception, Dagger, and Current Designs. A couple staff members are less than helpful, but most are quite good. (Note: Review applies to previous store location, have not been to current location.)
Great River Outfitters (Waterford) - Selling little else besides kayaks and paddling gear, Great River Outfitter's owners and salespeople are clearly kayaking experts. An emphasis on European products, with some unique boats and products that can be hard to find elsewhere.
Backcountry Outfitters (Traverse City) - Very helpful staff, even dragged a couple boats out to the river in March so we could go for a test paddle in the snow!
The Outpost (Holland) - Only folding boat dealer I know of in Michigan (Feathercraft). Good boat selection, including Dagger and Ocean. They also rent kayaks, but there is no way to return them on Sunday.
Nordic Sports (East Tawas) - Selling kayaks since 1976, the owners are experienced paddlers. Nordic Sports sells Perception, Current Designs, Necky, Valley and Nigel Dennis boats, plus paddling and camping gear.
The Outfitter (Harbor Springs) - The Outfitter carries a good selection of kayaking gear, including boats from Current Designs, Eddyline, Ocean, and Hobie kayaks, runs trips, and has boats available for rental.
Venture Outdoors (Canton) - Venture carries Wilderness Systems, Necky, Dagger and Perception kayaks, as well as paddles and paddlewear.
R.E.I. (Northville, Troy) - Given the growing popularity of the sport throughout the Great Lakes and the rich selection of boats at REI stores on the West Coast, the size and quality of REI's sea kayaking section is a little disapointing compared to smaller Michigan outfitters. However, they do offer several Perception sea kayaks as well as a number of smaller boats. REI's best feature is their selection of outdoor goods, this is the largest store full of quality clothes, packs, food, and other gear you'll find in the state. Sales can offer excellent prices if you can catch the items in stock.
Galyan's (Novi) - Galyan's offers sporting goods of all types, including a fairly good outdoor section on the second floor, and more kayaks than it initially appears - the better ones are used for decoration so you may have to hunt around. Selection includes Dagger, Perception, Ocean, and Old Town. The kayaking gear selection is strange - the basics are all here, with great selection in some areas, but poor selections in others. Friendly staff, but the ones we talked to weren't at all familiar with kayaking. Galyan's also has stores in Okemos, Grandville, and out-state, but we haven't visited those.
E.M.S. (Farmington Hills, Troy, Ann Arbor, Traverse City & Kentwood) - While their selection of kayaking gear is limited to Perception boats, they have some excellent sale prices on all kinds of outdoor gear. Very impressive customer service. The Farmington Hills store offers rentals and I believe the Traverse City and Kentwood store do, too.