08/07/2012 at 04:15 PM EDT
Chicago got a taste of Hollywood over the weekend, as stars made their way to the Windy City for the Lollapalooza music festival, where a slew of acts performed, including Red Hot Chili Peppers, Florence + the Machine, Kaskade and Avicii.
, who has been spending a lot of time there with her Chicago Bears beau
Brian Urlacher, skipped the festival itself, but took part in some festivities, sans her man.
Arriving at the Gilt City Better than Backstage rooftop brunch, the Playboy cover girl
– clad in a pair of M2F Brand Denims and sky high platform shoes – nibbled on veggies and dip, and took in the skyline.
"She looked very happy and seemed really excited to meet Chicagoans at the party," an onlooker tells PEOPLE.
Also on hand during the weekend was Breaking Bad
star Aaron Paul, who went so far as to snap a shot of himself at one show, surrounded by a huge group of concert fans.
"At the show, he was with his fiancée," a source tells PEOPLE. "They were on stage and hanging out backstage, watching Miike Snow with [a large group]. He was the photographer of the group, taking a bunch of shots from his HTC One phone."
The weekend was apparently a win for Paul, who Tweeted
, "Dear Lalapalooza (sic), I love you. Sincerely, Me."
hunk Joe Manganiello had dinner in the city's popular restaurant, Paris Club, where he munched on lobster crostini, lamb meatballs and filet mignon, while sipping on nothing but hot tea.
"He tried to remain under the radar," a source tells PEOPLE, adding that he failed to go unrecognized and had women pointing at him.
The big weekend brought out other couples.
David Arquette, who has apparently reunited with on-again gal pal
Christina McLarty, headed to brunch at Hub 51 with his lady love before they made their way to the festival.
Managing to go seemingly unnoticed, a source says the couple was "certainly not shying away from showing affection."
Another pair packing on the PDA was Kelly Osbourne and new beau Matthew Mosshart.
Heading to the Hard Rock Hotel Chicago for the Rock the Vote Nights party, the lovey-dovey duo continuously snuck in kisses.
"He knew people were looking," an onlooker says. "But he didn't care. He just kept leaning in for some PDA."
After taking goofy pictures together at the Ck One-sponsored bash, the twosome met up with Kelly's brother Jack. According to the insider, Kelly was "happy to take photos with adoring fans." – Jennifer Garcia, Patrick Gomez and Lesley Messer