I have a, hopefully, worthwhile suggestion...u nlike the previous post. If we send our photos to you early it may be best not to post them until the contest time, because then they will get old and it will be harder to vote, right?
Some ideas, too:
Mobsters and movie stars
Ethnic
Hot dog costumes
Cowboy and Western (already said, I think)
Crazy drivers (dressing them up and putting them in the driver's seat)
Animal theme (disguise them as another species)
The Homemaker (kind of like "Calendar Girls" where the scene is dog as homemaker baking, etc.)
Tough Tails (Bikers, body builders, wrestlers, boxers (literally), martial artists, bouncers, hit wo/-men, etc.)
80s Theme - (Madonna, Prince, Tina Turner, etc.)
Eras (Like the flapper idea...Victori an, Gothic, Medieval...sev enties, Greeks, Romans, Egyptians)