If I'm going to have to negotiate across a table (rather than over something less formal like golf or dinner) then I'll usually have a few people spend the week in advance getting me data - piles and piles of data. On the whole I like to think I'm an amiable person face to face and like to keep that during discussions. Stature also helps though - it's ridiculous but being taller and generally bigger than the other person puts one in a position of strength. Most of the time I'll speak with an entirely regionless accent, but certain types (especially your stereotypical proud Yorkshireman) will get their backs up as soon as they hear that - in which case I can speak as colloquially as anyone on our shop floor. I find negotiating with women helps - I am an incredibly beautiful specimen of the human form and can usually bring negotiations in my direction fairly easily (that last bit is mostly a joke, but a little bit not).When you go into these negotiations Scara do you ever think what you would say / do / want if you were in the other persons position? I cant be bothered to go through every point you bring up as until its played out we do not really have a definitive answer - looking at both sides it certainly appears to me that we are negotiating from a position of weakness.
I find that the right questions and well-placed silences will ensure the other person/team has played their hand fully before I have to start on what I want. My trick really is to ensure you have thoroughly exhausted all of their fronted and hidden demands before you start talking about your own - that leaves them nowhere to go once you start picking things off.
Mostly though, I don't get into this kind of negotiating with customers or suppliers - it doesn't lead to a healthy working relationship. This stuff is for regulatory agencies, councils, etc. - those who begin from a position of being antagonistically difficult.
In answer to your question, of course I analyse what the other person or people want/need. The two most important factors in this kind of negotiation are to simultaneously, fully comprehend the human element behind their wants and needs and how they can convince themselves they are fulfilled without being so, whilst having a complete disregard for them as a person. They are merely a tool with which you can lever the situation to fit your needs.