K-On!, Shirobako Recommendations
Both animes start off with an all girl high school cast as their main characters struggling to get something ready for their high school festivals and before graduation. What Shirobako does, is graduate them within the first episode, and then show what the girls are doing in college/work. If you enjoyed the feel-good, moe, and struggles of K-On! you'll see some parallels with the cast from Shirobako as they struggle to meet their deadlines in all their girlie cuteness. Highly recommended.
Shirobako feels much like the K-On series: It's a comedic, light-hearted anime that centers around a group of young female donut-addicts, who upon graduation, vow to one day create an anime together. In a very cute manner, the show documents the girls struggling to keep up with their work, and furthering their careers while attempting to adjust to their new adult lives. One can also appreciate that Shirobako is filled with great references to many iconic shows of the past few decades. (Initial D, Gurren Lagann, just to name a few.)
Both feature a cast genki girls.
In both anime the girls start off in highschool.
The plots are cheery and fun, but with slight hit of drama and psychology sprinkled all over the series.
Both are swell as hell.