Qsl cards

Of the four you presented I would go for the one with the dam and bridge as the dam started the rise of Phoenix and the cities around Phoenix.
I think this would be a good centennial QSL card. As for Mesa ARC QSL card I would use Red Mountain with an antenna on the top putting out simulated rf waves. Red Mountain is just north of Mesa and stands for the area that most of the members live and work in. I don't have a picture of Red Mountain to play with but when I get my camera fixed I will give a try at producing something.
Dennis Burks
KE7YLV