Star sightings: John Popper, Brandon Marshall, LeBron James

SEEN ON THE SCENE: Chicago-based improv queen Charna Halpern reports fans of John Popper of Blues Traveler got a huge kick out of seeing him sitting in with “Opening Night: The Improvised Musical!” at Halpern’s iO West in Hollywood. … Recent dinner sightings at Gibsons on Rush have included the Bulls’ Taj Gibson and (separately) Mellody Hobson and hubby George Lucas. … Over at RPM Steak, NBA stars LeBron James and Tristan Thompson chowed down on colossal prawns, crab legs and other assorted goodies. Also at RPM Steak, football was on the menu for the Buffalo Bills’ Blake Annen, joined by Pat O’Donnell and David Fales of the Bears. Other sightings at the steakery have included “Chicago Fire” actress Monica Raymund and the Hawks’ Dennis Rassmussen, Erik Gustafsson and Viktor Svedberg. … Country music star Lee Brice made the scene at Joe’s Live in Rosemont, after his recent performance at the Rosemont Theatre. … New Bears offensive coordinator Dowell Loggains dined at Harry Caray’s in River North, while at a separate table the Sox’s new TV announcer Jason Benetti joined Sox veteran announcer Steve Stone. Also at Harry’s on Kinzie: Brandon Marshall and his wife, Michi, celebrating the success of the charity event for their Project 375 Foundation at Susan Sarandon’s recently launched Spin ping pong club. … Bravo’s “Southern Charm” star Shep Rose was spied at the bar at Le Colonial on Rush. … Derrick Rose got his barbecue fix the other night at Chicago Q on Dearborn. … Finally, a big congrats goes out to one of my fave teen hangouts: Jim and Pete’s in Elmwood Park — and owners Michael Bucchianeri and Jim Sorce — celebrating their 75th anniversary. As part of the fun (running through the end of this month), diners will be given gift cards with their checks — good through Dec. 31. Amounts will randomly range from $10 up to $1,000.