There are 4 of us in our group. We walk through everything, and stay together because we like to bounce ideas off each other. We do not walk slow and do not waste time. There are things there that just aren't of interest to you and not worth wasting your time on. I would say, get a map of the lay out and target the area's of interest by importance and location. For me, I could care less about 24" wheels, I'm walking right by those and not stopping (unless on of their spokes models needs their pictures taken with me.(Ron Burgundy voice) I'm kind of a big deal). A day and a half will have you taking in a lot. Take pictures so you can remember it later. You will see so much there, that you will not remember it all. We are in there at 10am till 5 or 6 pm and we know there are things we don't see. Make sure you check the schedule for things like the drift show, if you plan on watching them.
Where comfortable shoes. You feet are going to be killing you. Also, if you have one, bring a rolling tote bag to put the free stuff in. There are more free mags than you can carry. Look for the free subscriptions. Look for free samples on car cleaner, flat tire repair, and tons of other things.