Why do you want that? (Be careful about your tone.)
How would [what you are asking for] help you? If you got that, how would you feel? (Use identified feeling as the next level of interest and perhaps repeatedly probe for levels of interest below that.)
Why doesn’t what [the other person] is suggesting work for you?
In a dispute, people often don’t get all that they want. What do you really need to feel satisfied?
What do you need to get so that you can leave today feeling good (or okay) about the settlement or that you can at least live with?
It sounds as if what you are really most interested in is _____. Is that right?
Some people in your situation might be concerned about ___. Is that a concern for you?
What do you think are [the “opposing” party]’s underlying interests in this situation?
Which of these interests, if any, do you share?
Is there a way you can think of that you can achieve your interests and also allow him/her to achieve his/hers?