I was just searching and saw some cold hardy banana trees. I love the looks of the 'musa' - Hardy Fiber banana but I'm not familiar with them. I still have no idea if a tropical would look out of place with the other plants.

Musa basjoo is the only banana that will survive your winters with no protection. They dont usually look out of place with native trees and they go great with cannas and elepahant ears. Needle palms are your best bet for a cold hardy palm. If you get a large one you wont need to protect it too much. This winter got to 14F by me, but I got lots of snow. My needle palm got no protection and its still doing good. Windmill palms can handle 5 and will need protection in your area during the first winters, but they can get pretty tall (maybe up to 20 feet in 20 years from a nice sized plant.
I have a pindo palm, its a really tropical looking palm but only cold tolerant to 15F before damage really begins so it will need protection especially when it rains in the winter.

If you plant them right it will look really good with your tropical plants. It seems like your shrubs kind of have a little english style to it, and windmill palms as well as needle palms are seen in english gardens (and I can picture some knockout roses under a windmill palm, but it will be hard to protect)
Southern magnolias are also good tropical trees and will survive your winters fine. They do great here, only disappointing thing was that since they are evergreen trees, one of them did lose a huge limb from the heavy snow this year, but all the others were fine and snow like that is rare.

Also there are hardy hibiscus that have the same great flowers as the tropical ones in the summer months, and lose there leaves for the winter. They will never have a problem from the cold in your winters and some of them can handle zone 4 winters.

There are so many more tropical plants that can live in your zone and many can fit in your landscape well. The palms and cycads forum, this forum, and the bananas forum are some forums that have people that are growing some nice tropical plants in cooler zones like zone 7s and even cooler.

Good luck.

Thank you so much for the information. I was actually looking at the musa banana and the other two palms you mentioned. I am going to start looking into that when the weather warms up.

They're not visible in the picture but I do have lots of cannas, a few hardy hibsicus, and tropical hibiscus. One of the hardy hibiscus has been in a pot for 3 years now and still looked great last summer.

We also got A LOT (3-4') of snow in one week last month and some of my plants really took a beating but others bounced back without any damage.

I'll second those recommendations. Musa Basjoo is a great tropical look and easy to overwinter. As far as palms, trachycarpus fortunei, the windmill palm, would be the best for your specimen application. Just make sure you keep the snow and ice off the spear. Moisture, not temp are the problem with them. The pindo may work, but it will take a little more love during the winter.

Your poor landscaping looks pretty nice already!

Musa basjoo should do well and would look nice there but may grow too big. As an alternative you could consider some of the larger cannas, especially 'Musifolia' which give a nice tropical look, do well in our heat and humidity, and will stay a little more in bounds. Some of them are relatively hardy if mulched well (although I haven't had much luck overwintering any cannas in DC).

BTW voles seem to love palms, so that might not be a good choice if they are a problem in your area. Even bananas and cannas might be vulnerable. If you don't mind replanting annually, some of the larger castor beans like 'Zanzibarensis' or 'Impala' would look very striking in that spot, and I doubt any voles would touch them--just keep in mind that the seeds are quite poisonous (although it's easy enough to cut them off).

Oops, that should be "your POOL landscaping!