Instruments
Minnesota

Here is a list of places to look for musical instruments in or near Minnesota, with this understanding:  I am only including shops with which I am personally very familiar and which I have found to be competent to guide a buyer well.  This does not mean there aren't many others equally good.  Even the big chains have some very good people working for them, who have the breadth of knowledge I value.  But my standard is that every time you go in, a knowledgeable person will be there to answer questions.

In the Twin Cities

Charles A. Hoffman Guitars
Charlie Hoffman's shop on Franklin Avenue in Minneapolis is the warranty station for virtually every fine make of acoustic instrument.  In addition, Charlie's own handmade guitars are superb -- they're hard to come by, but he often has two or three on the wall, along with a handful of other stuff.
Homestead Pickin' Parlor
Located in Richfield, south of the intersection of Penn and 66th St., this is my favorite music store in the world, and I am a searcher for places like this.   At Homestead, Marv and Dawn Menzel have created something most unique -- a business which also functions as the center of a community.  As to instruments, I think it's fair to say that Homestead doesn't have the most instruments, but it certainly has the widest variety of kinds of instruments.  They sell guitars, mandolins, banjos, autoharps, hammered dulcimers, Appalachian dulcimers, bowed psalteries, bodhrans, fiddles, mandolas, bouzoukis, bones, clappers, noisemakers of all kinds, tin whistles, and on and on.   I don't think anyone in Minnesota has more banjos than Homestead.  The shop is small and crowded, and I have wasted weeks of my life being delighted by the place.
Podium
The Podium has been around forever, in the Dinkytown area just off the main U of M campus.  It is a great place for the classical guitarist to find a fine guitar and the sheet music to go with it.  However, the Podium also has become the local shop with the largest number and widest variety of fine acoustic steel string guitars.   On any day, there will be a bunch of Martins and Taylors, along with Collings, Santa Cruz, Goodall, McCollum, Petros, Hoffman, Lowden, Larrivee, and other fine makers.   A guitar player's paradise.
Willie's American Guitars
Located in St. Paul near the corner of St. Clair and Cleveland, Willie's used to be (and still is) a mecca for electric players.  However, in the last few years, he's built a very nice acoustic room, where he has a nice variety of new and used guitars.   Probably the best place to find a used Gibson acoustic, and Willie's is the local dealer for those very fine new National resonator guitars.  Another must to visit.

Instrument Repairs and Setup in the Twin Cities

My instruments have gone to Charlie Hoffman's for work for over 30 years, and I am always happy with the results.  Homestead has also always had a fine repairperson.  I have not used either the Podium or Willie's for repairs, but they are so knowledgeable that I wouldn't hesitate to do so.

Away From the Twin Cities

Dave's Guitar Shop
LaCrosse, Wisconsin, right on the border with Minnesota.  If you are ever in the LaCrosse area, stop at Dave's.  He has the largest selection of electric guitars around, and a room full of collectible electrics which is a history lesson in itself.  There is also an all acoustic section, with lots of things to play and see.

Spruce Tree Music
OK, so it's not really very near Minnesota.  It's only 4 hours away, and it's funky, and I like Will (the owner), who knows guitars really well.  If you're going to or near Madison, Wisconsin, stop in and see this very fine shop, dedicated mostly to acoustic stuff.  He'll usually have a few old Martins and Gibsons, and he's sure to have a nice collection of new guitars, banjos and other miscellany.