I wrote out a long one much like Erin's, but then realized how (a) the longer it is, the less likely they are to read it and (b) how many policies in some of those sample birth plans are already covered by our hospital's not-terrible policies. Also, I knew my midwife would be going with me if I had to transfer. So I basically pared mine down to the overarching essentials, more or less: I would like my birth to be as natural and private as possible, and I do not consent to any intervention without consultation. In the event of an emergency, please consult with DH before proceeding. Then I made sure DH knew all of my wishes in the event of a c-section, etc.
I think you said it all... as long as you know that somethings (if not all, as you said!) may change then I would put anything and everything on there that you would like! I wrote mine up this last time, and I think the only things that stayed the same was baby being put on my chest immediately after birth, the room was kept dim and quiet during L&D, and baby was never taken from me. All else went by the wayside lol! Oh well, as long as baby arrives safe and sound! Good luck!