I'll go over some of the ones I've seen which you might like. I'll add a little synopsis so you can assess for yourself whether you'd like it or not.
Laputa: A mysterious girl with magical powers literally falls from the sky and teams up with a plucky orphan boy to find an otherworldly realm.
Kiki's Delivery Service: A young witch and her talking cat travel to a quasi-European town and she starts a delivery service, befriending a flying enthusiast and two old ladies along the way. This one especially is very slice of life.
Ponyo: There is a reclusive mad scientist who lives under the sea and genetically engineers fish-hybrid children. One escapes and she makes friends with a local boy. It's a very simple story but classic Miyazaki visuals.
From Up on Poppy Hill: Umi and her friend Shun unite to save their high school's old but vibrant clubhouse. There is a melodramatic romantic subplot but it isn't nearly as interesting. I'd say it's still worth watching if you like Ghibli movies.
When Marnie was There: This is a personal favorite of mine. Anna, a foster child, goes away to her aunt and uncle's house in rural Hokkaido on doctor's orders. There, she finds a mysterious old mansion and the girl who (sometimes) inhabits it, Marnie. There's a lot more to this one but it's hard to talk about it much without spoiling it.