I haven't yet started my new Traveller game and in fact, may hold off for a bit.
One of my players voiced his concern that he really wasn't up for starting another new campaign as, with limited days and times available for us to play, it would cut into our ability to do more Champions, which he is loving.
I sometimes work Saturdays and that's the only day all three players and I can coordinate. This current Champions campaign is turning out to be one of my best in a long time and I don't mean my best Champions game or even my best Superheroes game. I mean the flat out coolest, craziest, deepest, most rough and tumble RPG campaign in a while. If we have a Saturday available to us, the guys want to use it to play this game. So do I. Make no mistake, I am loving this game.
As I've noted in the past though, I do suffer from gamer ADD like so many other GMs and more so I am just that type of guy who can only eat even my most favorite food so many times before I get sick of it.
So, periodically I start looking toward other ideas and options. Sometimes I can make them work with what I am currently running and sometimes I can't. Most often I can't. I pretty particular about genre. If I am running medieval fantasy and think up Star Trek ideas then I want to run Star Trek. I don't want to stick Trek into my Ars Magica or something. Just not my cup of tea.
For now, I am not going to start anything new with my main group until we either finish with Champions (not likely for a good stretch) or everybody begs me to try something new (highly unlikely at this point) or my schedule free up.