I think everything I like doing in the game, most would consider a waste of time. ^-^;
Like some people here, I also work at the hotel every day. Gotta make that free 150,000 just because! While I'm in Lumiose, I also check the Loto ID place daily.
Speaking of daily, I have a routine. Aside from the Lumiose stuff I just mentioned, I battle Psychic Inver at the Inverse House every day. And from 8 to 9 p.m. in-game, I'd search the region for Mega Stones. They're pretty tricky to find, but I have most of them now. And I usually check on my berries at the berry field. While I'm on Route 7, I'd sometimes make a round in the Battle Chateau.
And if I could, I'd love to make more PR videos. Alas, there's only space for three videos and I'm reluctant to delete any of them... >_< I spent quite a bit of time on them, and I find it a lot of fun.
I also like sitting on benches. I'm pretty sure I've sat on every single seat in the game at least once. :P