I met Jay Leno when I was on the college committee that booked him to do a show. This was when he was still doing standup and hosting The Tonight Show when Johnny Carson was off. He was kind, friendly, and jovial beyond all measure. Swell guy. He is also a VERY LARGE MAN in person - a towering, thick fellow. They say the camera adds ten pounds? Well in Leno's case it subtracts 50. He's yuge.
Alex Trebek, on the other hand, is a teeny-tiny, wee little man. Met him, also in college, when I tried out for the Jeopardy! College Tournament. He's friendly but kind of cerebral - sort of like that quirky English professor you had in college.
Downtown Julie Brown was friendly, but super quiet and soft-spoken. Saw her at a gift shop in Daytona Beach, Florida, surrounded by her crew, during Spring Break 1989(?). I only got to say a few words to her before her security guy started pointing towards the door, indicating that it was time for me to go.
Ran into Gerald McRaney and Delta Burke at Pat O'Brien's in New Orleans at Mardi Gras 1995(?). Gerald had been the Grand Marshall at one of the parades, and by sheer chance we were seated at the same table later that night. I was hammered and knocked my drink over, spilled it on both of them! :O