Miele
I can only highly suggest Miele for a verry efficent DW which has a huge capacity (once you learned how to use it), cleans perfectly and has a genious drying system.
Though Mieles do not have a exposed heating element, they use a special drying system called "Turbothermic" drying. Basicly, a fan sucks the warm moist air out of the cabinet into a pocket at the side of the DW. This condensation-pocket is actively cooled by another fan. This condensation system boosts drying performance without the usage of an heated dry. This system made it famous for its ability to dry at lower temperatures and independent of the water intake temperature. But as with any modern DW, you will probably have to use a rinse agent, but Miele even suggests to use vinegar or citric acid if you don't like to us rinsing agents. (There were limitations on the acidity, but I can't remember them right now. If you like, I can check them!)
Further, if you really invest on a higher end model, there is the AutoOpen drying avaible as well. Basicly, the dishwasher opens it self after the cycle is finished. This allows for improved drying even if you do not open the door right after a cycle.
The cycle you'll probably want to have is the sensor cycle if you want to save on water and still get the optimal result you exspect. This sensor-cycle uses 3 ways of sensing to adapt to the load and thus can wash in any way from the short 1 hour wash without pre-wash and only one rinse with a low temperature profile (not more than 120°F) for a small lightly soiled load up to a (theoretical) wash with up to 2 pre-washes, a long main wash at up to 150°F, 2 interim rinses and a final rinse takeing 2 1/2 hours. Should this not be enough, you will always have the option of the intensive cycle that washes at a whopping 167°F. The maximum usage of ANY cycle is no more than 7 gallons, but the average cycle will use anywhere from 2 1/2 to 4 gallons.
As there are many lines of Miele DW (DW means DishWasher), I xan't explain you all the differences and options. But the playlist I'll attach does a pretty good job of it.
The only thing you want to care about is how far away the next Miele service is loaceted from you. Though you should get trouble free service for at least 10, but at such light use rather 15 or 20 years with minimal care (clean the filters every other month, run an empty intensive cycle once a year etc.), something always can go wrong. And Miele service is not the cheapest. But again, if want to be on the safe side, you can extend your warranty to 5 or 10 years directly from Miele. This extension gives you the full coverage your basic warranty does: No charge for parts and labour, no matter what might go wrong and of course the true Miele service (no other service company, any service job would be actually done by Miele).
Hope I could help you a bit (and my english is not to bad, i had a LONG night).
Have a nice 2015
Henrik
