Very clean and creative designs, great font choice. I like #1 and #2. The pyramid shape on #3 may lose some people. On #1 and 2 would it be possible to make the weight plates the same diameter similar to olympic lifting plates? See photo example:
http://1.bp.blogspot.com/_6eI8rvbyphA/SnwfI1gb-PI/AAAAAAAAATA/dtQTn17iyko/s1600-h/Pendlay+Bumpers.jpg