I did it! For the past few months--well I guess as long as I've had this damn thing, I have been struggling with my image sizes--I feel like they come up really small, and when I would try to set them to "Extra-Large" they would get cut off vertically. I tried resizing the image manually before uploading, but no success. Blargh!
So then I decided to start digging through the Blogger help forum, which I figured would be anything BUT helpful, as those FAQ's and forums usually are, and lo and behold, someone was having the same issue. The solution: PICK A NEW TEMPLATE. D'oi. So...finally...a nice big image to stimulate your little eyeballs.