can i suggest you have a look at www.raceshoptours.net for a day long tour around a good number of the race shops. Although other companies may do this I would wholeheartedly recommend this one.
I travelled to NC from Glasgow Scotland and could never have got myself around the race shops myself. Trisha, who is the owner made a special journey into uptown Charlotte to pick me and my mate up and really made us feel special and made the tour. Her persona; touch and friendlyness is a way into to some of the aspects of the garages you just wouldnt see as all of the staff know her and help her out with "extras" when they can. I watched the 88 pit crew train and had a chance to chat with some of the crew and also got a lug nut directly taken of a 5 car.
Since i got home from Charlotte in 2010 i have kept in touch with Trisha such was her friendlyness. She made that tour and along with the races was the highlight of my trip to the states.
I can also recommend Speed Street however as a non US citezen there was a lot i couldnt take part in! Oh and the Hall of Fame - Awesome!
Currently planning Daytona for July. so excitied!