I like your design.
I wouldn't add any more detail to it, looks good the way it is.
The top really needed something to blend in with the sides, if you where to just leave it blank I feel it would look a little strange and un-finished.

If your unsure of it Mike, then just do some more drawings and see what you come up with.
You will either find a better one or you will come back to the one you have.