Saw the most common Japanese red-barked maple, Sango Kaku, in containers on the patio at Winterthur Estate and Ilex verticellata in containers at Longwood Gardens. Quite impressive. Longwood had a yellow barked Cornus in a container. I use the Japanese Maple called Fjelheim in the same fashion, moving the pot about during different Winters.
Did buy some bluestar junipers to place in pots to get through the Winter, but neglected them, and they are not pretty, but the ones I have in the ground are wonderful Winter accents. Did set up a Christmas tub outside church with moss and a central dwarf Ilex verticellata 'Red Sprite'. It looked good until replaced in Spring.