The teacher discounts are standard at 149 a night I think for the Dolphin and a little more for the Swan. I think the teacher discounts are the lowest you can get. Did you try calling yet? Its probably not too early because I don't think the teacher discounts expire.
I'm eligible for the teacher discount too, but I haven't even thought about using it yet. I'm curious, what do you think makes the Dolphin so appealing?
Here's some info off of mousesavers:
"Government employees (federal, state and local), active duty military, registered nurses and certified school teachers qualify for great rates at the Swan and Dolphin -- usually lower than the Annual Passholder or Entertainment Book rate. The rates for nurses, military, teachers and government employees start at $139 for the Dolphin and $149 for the Swan, subject to availability.
You must book the military, teacher and nurse rates directly through the hotel at (888) 828-8850