I've learned that creating a banner for an exhibit tent is very different from creating a banner for a blog or a website. I thought I could just take images of my artwork and stretch them to fit. Hah! By the time you take an average painting and make it fit a 10" x 60" space it is quite pixilated and no amount of adjustments in Photoshop will make it any better.
So, I just created a banner from scratch, making the original size 10x60. I think I like it. Of course, it's 2:00 a.m., too, so right now I'm not in a position to make any long lasting judgments. I'll look at it again once I've slept on it.