Solo Palace of the Dead / Heaven on High / Eureka Ortho is amazing fun!
I don't like to do treasure maps with randoms, I play it with 1 friend. So my tank friend and I as DPS (If lucky at final boss floor I switch to healer,unless toad boss)
Not only because it is more fun with my friend, but it takes more time to kill things, and during it, we talk about many random things and meme about the monsters.
We also refer monsters by food types, and laugh about everything. Otherwise, we que to get the mount or crafting material for the barding, and scream when fail !
I think there is a lot to do, but it does not need to take too long, as long as the 1-2 hours you spend in the game are enjoyable, rather than AFK in Limsa, I feel it is good.
If nothing of this interest you, I think decorating apartment and taking pictures of each room corner is a lot of fun. It was something I use to do a lot.
Because there is so many furnitures, bringing out new idea room decorations, and crafting them by your own hands, it feels like building your own home in new styles ^^