Greetings!
You might need to use the arbitrary marker spacing. (click on the legend and look at the options) YOu can then assign a new color to each increment you select. You can also play around with the gradients, (color interpretation) but I suggest you only do that after you have your markers where you want them. I'm sure you can get nice results with the intensity graph.
Eric
Eric P. Nichols
P.O. Box 56235
North Pole, AK 99705