I did a hood demo at a car show I was at...
5 sections:
sanded and three stepped
three stepped
two stepped
one stepped
untouched middle section
This will show people the differences possible...full correction down to gloss enhancement only with MINOR defect removal.
Leather seat idea would be great to show off, and I agree, get an exotic car there under your booth...the "oh, he works on exotics, he must be good" mentality is what most people have (too bad its not always true!)
flyers, brochures, discount cards (I like the expiration date idea), a sign/banner would be necessary and an attention getter. Pass out free cookies and give people a reason to talk about you later ("did you see the detailers booth, yeah, well did you get those cookies...delicious! no, Ill have to go back (at this point you can remember them hopefully and strike up convo again))
Get a Laptop or LCD screen, I think a 7" digital picture frame is too small, and I havent seen many larger ones with high quality. Heck, I'd use a 42" plasma if I could!
Raffle is nice, free stuff is always a hit! Just make sure you put your name on the product somewhere so they remember each time they use it
Tons of ideas still....