Lots of variables. Will you use custom cabinets, with extra deep drawers, or just pull standard cabinets out from the wall, using a 2x4 frame or ledger and floor cleats? Keep standard depth uppers, or use 15" or 18" deep uppers?

How long is the cabinet run? What type of countertop material? Also depends on whether your supplier/fabricator charges by the slab, or by the sf. Ap 4.25sf total for the extra 24" base cabinet (accounting for 1.5" front overhang), compared to ap .375sf/linear foot for the whole run (difference between 25.5" and 30").

My opinion on either option would depend on the layout--how wide are the aisles, or how much floor space is available? Is the aisle too wide, so that closing the gap by 4.5" will make it more functional?

I pulled standard base cabinets out on one side of the kitchen by 3", using two 2x4s bolted to the studs, and I like the way it works. Some of the uppers are standard 12" deep, not pulled away from the wall, and I've never noticed a difference in reach. I have one 18" deep cabinet, which I don't care for--it's too deep, and I can't easily get to items in the back, so I think 15" would be good for 30" deep counters. The countertop material I used was salvaged lab table tops, so I can't offer a realistic cost comparison.

Thank you, mamagoose. I am trying to be cost conscious, so I would use regular base cabs. Probably a mix of 12 and 15 uppers. As far as the counters, I have no clue how they charge. Haven't discussed that at all yet! I guess I will have to iron it out with the KD.