Banners are selected sometimes months in advance and there are some members that have a large number they have submitted so you'll see their name pop up often. If you check the Site Banners forum you will notice that I try not to cluster members banners too close together but select from as large a variety of submissions as possible.
Rick, I see one banner in the queue for you.
The biggest problem for rejections are, as Dave mentioned, blurry shots, often with heavy pixelation. I wear glasses, if I feel like I need to take the off and clean them, it's too blurry.

And they need be vibrant. Winter snow shots don't really work. Besides, banners preferably should be related to plants for the most part. (some exceptions are made at times )

@Dave is right, I normally only use landscape photos, and Paul has a large number of nice ones. If you know of any good photos just tree-mail me the link, and I might use it. I do schedule months in advance though, so don't expect to see them any time soon. Starting in January we will be having special "Gardening Holidays" to replace some of the inspirations on certain days.

He does have a bunch of great photos!
I'm hoping to figur out this banner picture submitting this winter. I tried last year and I bet Sue laughed as she deleted. Something to look forward to.

Give it a try, Julia. My first submissions were deleted too. You finally get the idea of what makes a good banner. Do a lot of looking at previous ones.