A lot of my characters are 22-23 and I'd like to level up to finish the Shinra event for Sephiroth but it seems like I get shit exp from the normal dungeons yet when I try some of the easier elite versions, I get wrecked by the bosses. Am I missing something I should be doing?

I've been having fun with the game but feel like I might be nearing the end of my time with it if it's just a huge grind fest now. It's also pretty lame that character/game synergy is important but they don't give you anyone from V or VI.