Most of our trips, including our recent Disney trips, have been with friends.
The thing to ask yourself from the beginning is how important is it to you that you spend time together? In other words, would you be willing to compromise on some itinerary things because you want to spend time with those who came along? There is no right or wrong answer, only what you are looking for from your vacation.
I tend to state things as options for everyone, as opposed to rules. For instance, at some point before the trip, I/we will say something like "We're really looking forward to this trip. Of course, if you guys want to go your own way at some point, that's fine, since we may not all want to do the same thing..."
If you really want to stay together most of the time, you will most likely need to make some compromises on what/when you do things. But hopefully, you are going with people who feel the same way and everyone gives and takes. (Yes, this is possible. Our groups of 5-10 people rarely split up, and everyone has a good time.)
If you have certain things you definitely want to do, regardless of what the others want to do, just let them know what those things are and ask if they think they will be joining you or doing something else.
Things like sleeping arrangements, finances, etc should be worked out long before going, and the major things should be brought up when the trip is first planned. Again, though I mention them in casual conversation, as opposed to setting rules. "We wanted to know if you guys wanted to go to WDW with us in July? We have a one bedroom room through our
DVC purchase, so maybe you guys could just pick-up lunches and/or dinners?" Or whatever arrangements you work out.
The plus to travelling with generally the same group multiple times is that we've gotten all of that stuff out of the way. We take the 'stay together and compromise' route, because we enjoy each others company. And we know how we are going to split up any common expenses, and most of all, we stay flexible. Within reason, of course.
Are the people travelling with you going to be sharing your DVC room, or is everyone getting their own rooms?