This is the 6th year for the large banana tree. We dig it up by Halloween and store in basement, same with elephant ears and calla lilly. This is by the alley running by our house...lots of looks.
I have a bananna tree to and bring it inside when it's 50 F or cooler. Nice plant to have inside in the winter... very tropical.
If you want more tropical look for this area try a Norfolk island pine.
I love your banana, that would certainly make me do a double-take, even from the other side of the fence. You didn't specifically say you wanted suggestions. If you want a recommendation for another plant to add, read on.
I'd add some cannas to the oasis. This is my first year growing them and I really like them. Cannas are related to bananas. They're big, bold, and easy to grow. They also come in different leaf colors, and some will flower even in z-5, so they add some color. Plus they're another plant you dig in the fall and store in the basement. That's already working for you with your other tropicals. If you decide to get some cannas, do read up on canna virus first, and shop carefully. Getting virused cannas would be a bummer, especially if the virus spread to your beloved banana. It's worth it to spend a little extra and get one perfect, healthy canna, rather than a bagful of cheap but potentially infected ones. Healthy, happy cannas will multiply so your tropical refuge will get more gorgeous every year. The canna forum will give you lots of inspiration and advice.
Big guy is going to have bananas...big pod in the top.