My wall cabinet depth are 12", above the stove for thw microwave was increased to 15" and above the fridge is 24". I think its 12", but I guess you can do what works for you.

I have a mix of 12" and 15" with both depths on the cooktop run. If it's no upcharge...I would definitely get the 15"!

Yes, 12" has been the standard. But many of today's dishes (like dinner plates & platters) no longer fit in 12" deep cabinets, especially inset. I recommend you go with 15" deep. I wish now that I had made them all 15" deep. Those extra 3" also seem to make a big difference in storage!

No, the extra 3" does not have much of an impact on workspace below over the standard 24" deep base cabinets (25.5" deep counters b/c of the 1.5" overhang that extends past the cabinets & their doors & drawer fronts).

One last advantage...if you're short, it brings the upper cabinets 3" closer so more can be reached.

lol! i was wondering if being short they'd then be 'in my face'!

Thanks for the feedback! I'm sort of leaning towards the 15" just because I was looking at my current microwave (over the range) and it doesn't seem that much further out. But anymore feedback is appreciated - especially if someone out there has 14 or 15"! Thanks!

We put the 15" in one run of uppers, and had the base cabinets bumped out an extra couple of inches too. This adds a little more to the cost of countertop material. The installer added a perimeter strip as we didn't need deeper base cabs.
Dinner plates/platters now fit.
On the other side of the kitchen we had the 24" base cabs with 12" uppers.