With a catalog that spans from Barbra Streisand to Queen, the Beatles to Adele, original songs and many more, the “Glee” cast has quite the menu to choose from when it comes to naming musical highlights from the past six seasons. The group took time out at PaleyFest to talk about some of the most memorable numbers from their years at McKinley High, including the most challenging.

In season one the show took on its first tribute episode, “The Power of Madonna,” and  Jane Lynch says one song required more rehearsals and pre-production meetings than any other and was still quite the undertaking: “Vogue.”

“There was one step that I just didn’t get until they started rolling the cameras and it just happened magically,” Lynch said of the sequence, which re-creates Madonna’s music video for the hit tune. She laughed that she told the crew the one take would just have to be good enough, after the step didn’t come easily again. (Check out her moves at the 1:50 mark)

The episode also saw the girls tackle “Express Yourself” complete with headset mics and bustiers, after having rehearsal in the very same day. “We had done like five other musical numbers that day,” said Lea Michele. But “it was fun,” added Heather Morris, “we liked it a lot.”

Morris also recalled the thrill of re-creating Britney Spears numbers and dancing with the singer, whom her character, Brittany S. Pierce, was named after. “It’s every girl’s dream,” said Morris. “In seventh grade, you played her tape, or her CD in your room with your best friend, and you’re dancing with her.”

Spears guest starred in season two episode “Britney/Brittany,” which paid tribute to her music, with “Me Against the Music,” “Baby One More Time” and more Spears hits.

Though rather than Morris having the opportunity to perform with Spears, “Britney Spears got to dance with Heather,” clarified Darren Criss.

For Criss, learning his debut number was less of a dream and more of an unexpected challenge. Criss described learning “Teenage Dream” with the show’s first group of Warblers, most of whom were singers — “They weren’t dancers,” he said. Similar to Lynch’s challenges with dancing in “Vogue,” “It was the stupidest step-touch thing” that tripped up the group.

Criss still has the rehearsal video on his computer, “and it is so terrible,” he said. “If you saw it, you’d be like, ‘There is no way in hell this is going to be anything. This is pathetic.’” But thankfully, the fan-favorite number was edited well and it worked out, said Criss.

Members of the cast also told Variety about their favorite numbers that they did not have the chance to perform in, with Amber Riley naming season four’s rendition of the Spice Girls’ “Wannabe,” and Chord Overstreet praising Cory Monteith’s performance of “You’re Having My Baby” in season one.

“It was such an awkward moment, but he pulled it off and made it sweet and funny at the same time,” he said.

Meanwhile, Mark Salling pointed out Kristin Chenoweth’s first guest spot singing “Maybe This Time” as his favorite, and Jane Lynch went back to the beginning, with the original performance of “Don’t Stop Believin’” in the show’s pilot.

“That first one, just bare, stripped down, no costumes, no sets – I loved it,” she said.

For its finale, “Glee” will add another original song to its catalog, with “This Time,” written by Criss. The song is Lea Michele’s final solo in the series.

Criss, who has previously written for the show, said he felt guilty of pitching the idea of writing the final song but was excited that the show’s writers gave him the go-ahead. “I kind of wrote basically a love note to the entire series,” he said.

“It was a tough thing because I tried to encapsulate how I felt about the show, how I felt the characters would have felt about the show, and how the actors themselves feel in real life about the show,” and for the fans, “the people that have been experiencing [Glee] for all this time.”

While the song is a sendoff for Michele’s Rachel Berry, Criss explained that it also means “this time that we’ve had together has been so special. I did my damndest,” he exclaimed.

Michele said that “This Time” was the last song that she sang on “Glee” and was the last song that she recorded in the studio. “There could have been no other song that perfectly encapsulated the entire experience,” she said. “Darren really gave me the greatest gift.

“I got to say everything to everyone…that I wanted to say, but I can’t think of the words and he wrote them,” Michele said. “It’s so special – it was the most amazing memory.”

“Glee’s” series finale airs March 20 on Fox.