Since you mention sitting and swinging you legs, how about setting two of those base cabinets maybe 30 inches apart and then use a long counter top to span the space. Gives you kind of a desk to sit at. I would experiment w/ work bench height. I like mine kind of high. I am 5'9" and like a 40-42 inch bench. Some of this depends on what you are mostly working on at your bench. In my previous garage I used regular kitchen base cabinets and set them on a box built from 2x8s set on edge. I don't like space under cabinets unless it's maybe 15 inches tall. To me it just ends up looking messy. Get the bench height right first. Get a few cardboard boxes and set them on your kitchen counter. Use them to simulate different bench heights. I find I don't spend 30 minutes at a time on a task. So I use the high work bench and high chairs. Think those tall tables w/ stool type chairs that are popular in dining rooms and kitchens. With everything higher than the old standard chair/table dimensions it's a LOT easier getting up/down to get off and on the chair to grab that other tool or part you need that is 5 ft away. BTW, you may end up w/ the regular base cabinets spaced up off the floor while the 72 inchers are on the floor so you can actually reach into the top shelf.
