In host options you should be able to make yourself be in creative or survival mode while the world itself is on a different game mode and you should be able to do it to other players. Say you are playing hunger games but u want people to fly in survival so they can spectate. You can press there name and press 'can fly' or 'invisible'. Or you could maybe press there or your name and press gamemode 'creative' or 'survival'. You should also make downloadable plug-ins such as a faction or hunger games plug-in or something cool like that. If you guys like these ideas please do what it takes to get this post read by other people so we can make things like this come to the xbox 360 edition and expand our possibilities.
I don't think the mode switching will happen because of how the 360 stores the data. If I recall correctly, it would have to completely dump its cache before being able to switch, which is something I don't think it can do right now. Please, correct me if I'm wrong.
However, being able to let other people fly is a great idea. I don't understand why it isn't already in there. If I'm the host, I should be able to choose to give the other players the ability to fly or invisible. I was disappointed when I found out I couldn't.