Timbuk 3 sat next right next to me at Springsteen's Austin show on the "Tunnel Of Love" tour. They held hands the whole show. It was fucking adorable. The singer from Spoon was in the seat next to me when I saw McCartney at Jerry World like 10 years ago (note: my wife recognized him. I had no idea). I saw Chad Lowe (sorry, wrong Lowe) at a Cowboy Junkies show in Dallas in the late 90s. Saw Peter Reckell (Bo Brady from "Days Of Our Lives") at a Sting show at the Greek Theatre in '96. Tom Hanks was down the aisle from me at a Springsteen show at the LA Sports Arena on the "Wrecking Ball" tour.
Wait-- did I just follow Chad Lowe and Peter Reckell with Tom Hanks? I think I did!
Anyway, that's all I can think of, which is odd given the number of shows I've attended in LA over the years. There is one big ALMOST in this category though. Back in '92, my band was playing around Dallas quite frequently and I had to give away U2 tickets at Texas Stadium because we got a Friday night Trees gig, The Sugarcubes opened that show, and my friend Laura thanked me the next day for the tickets (they were great seats) and for the chance to talk to Bjork-- who sat next to her for the entire U2 show. UGH.