Have y'all checked out PicMonkey's collage/design options? There is a FACEBOOK cover design that is already formatted and ready for your personal touch. The only thing you need to do is insert pictures and/or graphics and you have an easy and personalized FB cover. I've been winging it for sometime using Picasa, but the last few I've designed using PicMonkey and it takes me about 5 minutes. Check it out.
My fall cover photo made in Picasa. Not too shabby, but not pre-formatted.
Made this one in PicMonkey. Much easier.
Here is my most recent FB update:
This time, I just made a photo collage.