What is the one piece of advice you would give about attending AXPONA?

It's your hobby, therefore, treat it as such and have fun. 

Pull out the Rolex, comb your hair and wear a sports jacket - that way dealers and exhibitors will give you the time of day.

Don’t forget the $400 shoes.

When I had a nice car, I thought about going to test drive other nice cars.

"Here’s my chance to have the keys of every mid-high sports/luxury car literally thrown at me, at every high(er) end car brand dealership I enter", I thought. The vehicular version of 'wearing your $400 shoes', to send the right signals.

Never did find the time to use that. Then I got a ’regular’ car again. Sigh.

I was wondering, is a black leather jacket still an indication that the person is very hip to the whole scene?

Day one complete. Covered a lot of ground. Feet don’t hurt too bad. Used many of your tips. Heard some very good rooms and some not so good rooms. Some were a surprise (good and bad). Not planning to mention which were which as I understand things can improve as the weekend progresses. 

I dressed casual this Friday morning. For me, it’s sweatpants, a t-shirt with an University of Iowa pullover and ball cap. And typically, from my experience at CES shows and Stereophile shows at the Parker House in downtown Chicago, it’s best for me to limit my exposure to not more than 2 hours of insanity with hitting listening rooms.

Besides, does anyone have familiarity with all of the gear in the room that includes the particular item of interest to them? I don’t.

A better strategy is to buttonhole the principles of the gear in which you’re most interested and try to gather a better understanding of that gear.

It is like hitting tasting rooms in Napa Valley: 4 tasting rooms is the max for me if I’m driving in wine country.

At least the public bathroom arrangements were well thought out on the upper floors.

And consider ditching your jacket in the car or at the coat check before going to the upper floors. The room A/C won’t be on in any listening room. And those rooms will have a lot of warm bodies present and very warm audio gear operating. 

OP: good luck attending and fighting the masses on the weekend days!