Well... you're one zone warmer than me, so maybe my suggestion isn't necessary, but what I would do is get those huge decorative pots that you like, set them where you want them, fill them with a good, durable medium... and then dig a hole and insert the potted tree or perennial that you want for your centerpiece. It can be removed and either brought inside, or placed inside a garage for better winter protection during its dormancy, but it could still be used in spring and summer as the main attraction of the huge pot.

Then, around that potted and sunk centerpiece, I'd plant a nice assortment of annuals or perennials you don't mind losing... or a nice ground cover, or something to trail over the edge.

So, in essence, you'd be able to lift out and change up the main planting of the large pot, but never have to move the pot or worry about the plant dying.

I'd probably go for those fake clay looking composite type pots, material wise... I think they'd probably last longer, and wouldn't crack like clay. I don't know if there's a material that's freeze proof. Some of those larger pots are rather costly, so it's probably wise to research a little and find out what material can stand up to your climate well. All I'm finding are frost proof and frost resistant planters from Google...

I'm not sure I helped you, at all... but good luck in your search! Another thought is to place the larger pots on movable plant dollies with wheels, so you can move them into protection if you need to.