Creating our CD cover and sleeve

We are now in the process of designing and creating our CD cover. We have been carrying out some research into popular CD covers.
Some of the CD covers are quite plain and simple, yet visually striking such as the Lady Gaga and the Jason Mraz one. The fact that they are only black and white makes them easy to achieve yet bold so they stand out to the human eye.
Other covers, such as the Coldplay one, are more artistic and creative, this is harder to achieve, yet creates a busy atmosphere which may reflect the album.
The Nickleback album is quite ambiguous, the cover does not give a lot away about the band or the songs, this may be effective in creating interest and wonder amongst potential buyers.