Yes, I use a checklist on intro flights and sightseeing flights. If the student doesn't see me using the checklist from the beginning, he's going to think checklists are a wimpy thing that he should discard as soon as I'm not looking. I try to fly the intro flight just as I would expect the student to fly his flight test.
On intro flights I talk my way through the start checklist, explaining what I'm doing.
On scenics, as I pick up the checklist before engine start I say something like, "Of course I know how to fly this airplane. I use a checklist for extra safety, just like on the airlines." (Unfortunately, the other day what popped out of my mouth was ".. just like on the Concorde." Deep in my mind, a Concorde is still a premier aircraft, flown by select, professional pilots, not the latest front page horror. I think I'd better install a better brain-to-mouth filter before I start flying pax scheds. :-o