anywhere else near worth chekcing out, im gonna go for exit festival which looks incredibly 180(http://www.autoadmit.com/thread.php?thread_id=5527991&forum_id=2#47658228)
timisoara is not far in romania - i have never been but looks similar in terms of being a college campus type city.
belgrade is interesting but only for a day. I would avoid mostly unless you ar elike deep into the arts scene and have some goth serbia gf.
Sofia, Ohrid, and Sarajevo are all great if you are spending time in the region. Budapest too but I imagine you already considered that.(http://www.autoadmit.com/thread.php?thread_id=5527991&forum_id=2#47658259)
https://preview.redd.it/croatian-students-wearing-nazi-ustashe-clothes-and-doing-v0-mai41ofzos191.jpg?auto=webp&s=2e128196fa025b9df7e2264070a54468c10b3e42(http://www.autoadmit.com/thread.php?thread_id=5527991&forum_id=2#47658279)