"It sounds all well and good to have a large array of things sitting along your countertop sink line" I do not think there should be an "array of things" along the back of the sink. The air gap is not required if you have a dishwasher with a high loop - dishwashers sold in the last 10 years or more come with the high-loop pre-installed. If you live in the one state in the U.S. that has a code requirement for an air gap (California), you put in the air gap for the inspection, and after that, replace it with an in-counter soap dispenser - as long as your dishwasher has a high loop hose. As has been said in this thread, use a batch feed disposal and you'll not need a button or switch anywhere for the disposal. I have a batch feed disposal. My sink has a single-hole faucet and an in-counter soap dispenser. i.e. two holes behind my sink. That is all.

I have a wall switch in the house I'm renting during the remodel. All along I have thought this was the bee's knees, because I was comparing it to my old situation--a switch in the sink cabinet, which had child-proof locks! What a pain that was. The wall switch is wonderfully convenient. Even though the wall switch is an improvement, it does have its down sides: I do occasionally flip the wrong switch, which really makes me jump. But something that no one else has mentioned here is that you often reach for the disposal switch with messy/wet hands. I think the air switch is slightly better suited for that kind of contact.

I see I wrote a comment on this back in 2011 when we had an air switch installed, but the sink wasn't working yet. Six years later, I'm a big fan of air switches. What I always hated about the wall switch (as still do in others' kitchens) is raising a wet hand to flip that switch. DD's switch also requires two steps to the left to reach it. In my sister's kitchen, finding which is the GD switch is always a guessing game. Water drips from your reaching arm onto the counter. It runs down your raised arm. I've always been a bit squeamish about flipping a live electrical switch with a wet hand. I don't miss it one little bit. Air switch vs wall switch kind of reminds me of the debate over the efficacy of taking your rugs out and beating them clean vs using a vacuum. Both work, yes?

PK66--as far as replacing the air gap hole with an air switch after the fact, I'll tell you what my plumber told me. He said that an inspector will usually look for the GD switch at inspection. If he doesn't see the switch properly wired, whether wall or air, and find it working, you won't pass. YMMV of course, but I think a soap dispsener is the only replacement you can use for an air gap. My soap dispenser, the air gap, and the air switch all fit in the same size hole. I LOVE having a soap dispenser, btw. No freestanding hand soap container knocking around getting gunky and leaving a soap ring on the counter. And even if I was on the fence about one, I'd take a functional soap dispenser over an ugly air gap any day of the week. :) Jane--looks great! Must feel good to have another decision behind you.