K.C.
I agree with everyone else, just make it special!
If you don't live in the southeast you won't know about Publix, but it is the best grocery store there is! All of the Publix stores around here have a few shopping carts with "race cars" or "rockets" for the kids to sit in. I love them because they also have a packet of clorox wipes attached to all the carts. Amazing. I also love that it is behind the cart (right where mom pushes from) so that they are not sitting on the ground in front of the cart, like some I have seen. This way I can still keep a close eye on my 2 year old and the 8 month old I babysit. It also has a double buckle so 2 kids sit safely.
Publix also has a kids club where they give out cookies, and as far as my daughter knows only well behaved chidlren are allowed to get cookies. We will usually stop by the bakery about 1/2 way through the trip so that the driving keeps her happy for the first 1/2 and the cookie takes us through the line. :)