I know it sounds weird, but I like restarting fairly often every now and then.
I'll beat the game with a basic team, and restart with a completely different team. I usually switch around the Natures/Abilities and the movesets a bit.. as well as the types I use.
When I get down to my last playthrough, I tend to find EVERYTHING, max levels on my pokemon, and attempt to finish the National Dex. Of course i'm not at that point yet, since I'm in the process of doing a challenge run. These things come and go, and it's always nice to know if you could've done your playthrough differently.