I haven't done one in a few years (gas is too expensive and my stash is too big). We hit 50 stores in 3 days and had a blast. We promised ourselves that we would buy at least a fat quarter at each store -- one store smelled so bad (cat urine and cigarette smoke) so we got our stamp and block and left (threw out the blocks because the smells had infused the fabric). There was also a store that only had reproductions (but no Aunt Grace) and we couldn't find anything we wanted.
I agree -- the fabrics that will be the focus of the shop hop need to be something that grabs me -- recently I have only liked one or two. I get annoyed when all of the fabrics have been presold -- very frustrating. We appreciated stores that had snacks -- we stayed there longer and bought more. We barely got to the last store (it was pretty isolated and hard to find), but we called the shop and the owner stayed open and we rewarded her by buying lots of fabric there (she had wonderful fabrics).
Some other ideas. It was real helpful when the stores had directions to stores around them. Have folks only cutting -- and someone else to ring up purchases. If you are stamping passports or have drawings to sign up for -- provide a place away from the cutting table to take care of that. Set up something fun to do (one year I helped with a demo to make the bias fringe strips -- the owner sold a bunch of brushes, etc). Have a new, eye catching fabric line (boy did I get in trouble when the store had a marvelous fabric line and other shops only had one or two of the fabrics in the line).