Ideal Group Work Situation

For me, the ideal situation for productivity and happiness when it comes to group work would be for all members to actually care about the assignment and willing to work. I know that sounds cliche, but that has been the root of all group work problems for me...people being physically there but not mentally there, or sometimes not physically there at all. It'd be nice for all members to be non-judgemental and open to new ideas, and be willing to share their thoughts. I've also experienced group projects where one member will present an idea, and the rest of the group will just remain silent as if they are a) afraid to say anything or b) don't care. That's no fun! Plus it's just not productive.