We bought a Bosch SHE55R56UC (500 series) two years ago and I love it! No third rack, but download the Bosch brochure of their models to see which options are offered on each model. I decided I needed the convertible silverware rack, foldable tines for big pots, all stainless tub, hidden controls, and adjustable top shelf, but not necessarily the quick wash cycle or rinse-hold.
In addition to looking at your sister's rack layout, visit a Sears or other appliance store to see the real differences in the rack features on different models. Some complain that the tines are too close together for stoneware, and some of my stoneware doesn't fit as neatly as shown in the loading diagrams (yes...Ze Germans at Bosch include suggested loading patterns in the manual), but I have overloaded that thing and rarely have to send a dish through a second time.
The Bosch dishwashers are great on energy and water consumption. Some complain about wet dishes, but if I wait for the drying/sanitizing cycle to finish, I have dishes too hot to hold and bone dry unless they have a recess in the bottom that catches water. (If I remember, it's not fan- or heat-driven, but a feat of vaporizing water from the dishes and condensing it on the sides of the tub)
Note the decibel rating...I think ours is rated at 44 db and it sounds like a gentle rain outside when standing next to it.
We got ours on sale at Lowe's for a great price (plus a mover's coupon discount)...delivered for just over $650. the 500 series you have listed is on sale for around $750 at Lowe's for the next few days.
I think you'll be pleased with any of those choices!

Here is a link that might be useful: Bosch Dishwasher Brochure (has tables of all the models' features)

Thanks so much etherealsunshine!