If you're not looking to be "efficient" (ie. won't run any other dungeons), Wanderer's Palace is pretty fun. Stalkers are pretty fun to run from - it always ends up with "OMGGGGG STALKER RUN FOR YO LIVEEEEEES!", and of course, Tonberries. It's a good place to run as well if you do not yet have your Titan/Relic Shield.

Otherwise there's Hard Mode Primals.

Unless you can't force yourself to get out of the repetitive grind for the efficient run to end game, then those are my suggestions. Take it easy and enjoy things as they come.