Sure does for us. I ran maybe four loads yesterday: scratch made pizza for dinner, "almost no knead" loaf of bread, and lunch for all. We had one or the other running most of the day.

There have been long discussions here previously on proper placement. I think the consensus has been to place them close together, by the main cleanup sink. We did it differently, with one by the main sink and one by the prep sink. It works well, with the main sink DW mainly used for dishes, and the prep sink DW more for pots and pans, etc.

It's a luxury (actually, we have a third DW in the basement which we occasionally use for overflow when entertaining, plus what a lifesaver during the kitchen renovation!) but one that we are happy that we did.

We tried them separated in our last house...One in the cooking area, one in the buffet area by the table and dish storage (Sort of like a butler's pantry, but open)...But what seemed like such a good idea in theory, was not in practice. That's why in our new house we have one on each side of the main/cleanup sink...and dishes are stored immediately to the right of the right-side dw. Part of our issue is the size of our family and that we need the flexibility to be able to load both at once and fit cooking tools in around dishes. We can't keep one for dishes and one for cooking. We have to use the space most efficiently for everything.

Many kosher people appreciate having two.

I wish we had the room for two dishwashers. We often have large parties and prefer to use china instead of paper. needless to say, the sole dishwasher runs many times.
I would put two in the kitchen, either side of the sink.
better yet, one in the outdoor kitchen so that we can wash the the all the wine and martini glasses...

We sit down and eat a candlelit family dinner every weekday evening. We rarely stay at the table for more than 30 minutes but it's amazing family bonding time that everyone has come to count on. Total clean up for this everyday "holiday" dinner is about 7 minutes...all the prep gear gets loaded into dishwasher #1 even as dinner is in the frenzied making; all the dirty table dishes are tossed into dishwasher #2 immediately thereafter. We have 2 Kitchenaids with multi adjusting racks so can fit in just about any pot, cookie sheet, or mixing bowl we own, even the lobster pot (things that don't fit, we've thrown away LOL). We scrape but do not clean or scrub anything by hand -- an excellent dishwasher should handle that with proper loading and proper cycle selection. Having the 2 dishwashers is a big time saver -- a big family time saver. BTW, we positioned the two dishwashers across and down from each other so there was one by each sink in our two cook kitchen.

A tip: take a big box of your pots, pans, platters, bowls, spatulas, and odd shaped favorites over to the various appliance show room and try loading different dishwashers. You'll quickly see which machines are going to work for you and which not. Some people love dishwasher drawers but I tried loading my stuff in them and realized they would never work for me.

We have two and it works great for us. As to extra cost, if you didn't have the second one, there would be the cost a cabinetry anyway, which would be less than a dw probably but still the extra cost isn't necessarily all that much. Great flexibility. Best thing is you can start to load the second one even before running and emptying the first one.

As to placement, remember you must have plumbing connections (H&C water and drain and probably a disposer) for any dw, and that usually means you have no real choice but to put them on either side of your sink, unless of course you have a conveniently located extra sink somewhere, and that second sink will probably need a disposer as well. Otherwise you may have significant extra plumbing costs. Generally, I'd just plan to have them on either side of my main sink.