I'd totally go for Cannas in that spot. They love all the sun and heat and water you can give them, and will keep on blooming through the summer. Look at Lowe's, they often have some fairly short varieties in nice colors plus the "Tropicanna" series with the amazing striped leaves. (this is not a great pic of them)
Cannas truly come in all shapes and sizes though, from 2ft. tall to 8ft, and with blue-ish, dark green, dark red, bronze, striped and variegated leaves. Flowers are in all the warm colors, pinks, reds, orange and yellows and also white.
These are some of the small ones I got at Lowe's a few years ago.
If you do plant Cannas in that spot, once they stop blooming in fall, I'd dig a few roots and just throw them in a pot of potting soil for the winter. That wet spot might well cause them to rot if you leave them in the ground. (depends how wet the winter weather is)
