Mix in ALL THE EXPANSIONS!
Playing IRL I'll sometimes use a Recommended Set from the rulebooks, but those only combine two expansions. I had a lot of fun* with the Dark Ages/Cornucopia set Dark Carnival: Band of Misfits, Cultist, Fortress, Hermit, Junk Dealer, Knights / Fairgrounds, Hamlet, Horn of Plenty, Menagerie
*warning: this lead to a very long four player game. One of my sisters had only played Dominion a couple times, and my other sister and my mother also took a while deciding what strategy to pursue, so it wasn't a terribly fast-paced set.