Dahlias get a bad press. They're seen as being out of fashion and the stalwart of the old school allotment holder and I have to confess that I only grew dahlias in my first year because they had been left in the ground by the previous plot holder, but now I grow them every year and I love them.
They come in a huge variety of different colours and shapes and are a perfect flower to cut and bring into the house, and the more you cut them the more they come back. They're easy to grow as well and will flower well into autumn until the first frosts start hitting. Once that happens and the leaves go black they need to be cut back and the tubers dug up and stored in a frost free shed in dry sand. If you live in a milder part of the country you may get away with leaving them in the ground if you give them a good covering of straw and compost - I wouldn't get away with this because my plot gets too wet in the winter and the tubers would be too likely to rot.
When spring comes and the tubers start sprouting it's just a matter of digging a big hole and putting them back where you want them. Simple! What's not to like about that?