I'm in GMT+1/CE(S)T timezone. But don't count me in for the next few weeks.
Also, we tried to have "themes" for a few weeks but as far as I know nobody really cared. Should we abandon the theme idea since it hasn't been successful so far?
We can have themes, but they should be an option, i.e. people should be encouraged to play a certain game type, but not forced to. And we don't need a theme for every week. If no one has a good idea, just leave it open.
Anyways, we should acknowledge that people may have arbitrary reasons for playing or not playing. Its things you cannot influence. The weekly list that you suggested may allow others to see who will be there, but it will only work if people don't mind being the first on the list (i.e. "no one will be there, so why should I be").