What gardening zone are you in - and is this a wet or dry corner? (or are you willing to water it a lot if you get a water-loving plant there?) Some nice suggestions already have been made - maybe add a bit of flowering low ground-cover along the front too.

Be sure to check the hardiness of whatever you get - you can't always count on your local nursery to only stock things hardy to your zone - some of them may require more coddling than you might care to give.