Not much has changed from my list over the last few years:
I really like the idea of playing a bandit and using your score to represent your bounty. Basically you are playing as the villain trying to increase the price on your head. Use the camera like they have on Dialed In to take your mugshot and put it onto a wanted poster for the high scores.
So much open source material: Excalibur, Lady of the Lake, Merlin, Knights of the Round Table, Dragons, Holy Grail, Castles, etc.
Monty Python and the Holy Grail
Very similar to the above, but more of a gag.
Steam Punk / Alternative History
I think something with Nikola Tesla could be pretty damn cool.
Campy zombies with Kill of the Week, Woodie Harrelson, Bill Murray, Emma Stone, etc.
I think it has appeal with adults and kids. Something with fun interactive monster toys like Monster Bash.
Man vs Machine, plus I really want to have an out of control Sentinel attack multiball.
Fables / Brothers Grimm
A mashup of the open source fairy tails.
Battle to save the world from disease outbreaks.
King of Tokyo
This would be my choice for your "giant beats" theme. It's a bit more colorful then what I think of with Godzilla or King Kong.