Replaced the float switch, and as a precaution, the heating element (although that part continuity tested good, but was 4 years old). This was after considerable research, trying to piece together information about this dishwasher. Common sense told me it would be a thermostat - so I found out that if it tests good for continuity (which it did), then its good, because it's a "high limit" thermostat. This was a relief because the thermostat is part of the drain pump wiring harness - $90. Glad I didn't need it! I was surprised the float switch is the demon in these dishwashers, but it makes sense if you consider this whole appliance is made of plastic, and it's trying to prevent destroying itself with heat if the water level is not correct.
The parts arrived sooner than expected (next day on a weekend!). We were delighted to get the dishwasher up and running again, the sooner the better, with a total cost of $64. Not to mention a great feeling of satisfaction having done it myself.