I was going to suggest the delica, basicly a short endura or an emerson stubby. Fullsize handle, but with a california legal sized blade...but it seems you wants a utility knife that won't scare the "gentle masses"
In that case I'll second (or third or whatever number we're up to lol) a simple swiss army knife. Rarely raises an eyebrow except for the worst knife-a-phobics, cuts well and "should" be legal anywhere a sharp is permissable. I perfer Victorinox over Wenger, for no tangible reason...
If a locking blade nesecary go for the Wenger if you want the classic sized swiss army knife, or Victorinox makes some locking models in there slightly larger offerings like the trekker.
Best of luck to ya

-Bill Liptak