there is always one idea per comp that is done over and over and over and the best remedy for this is, to write out several ideas out before you start designing and ignore the ones that were too easy to come up with.
I like the hawaii stamps. the square more then the round. and just to let you know, hawaii is not a seperate country and you do not need a passort to travel there, so I don't think it would have a stamp other then a United States stamp.