Can I go to the airport on my visa's expiration date and fly out the next day without facing penalties?

There will probably be a note in your passport, but if your overstay is only one day, there will be neither a fine nor consequences.

No big deal either way. It doesn’t matter

You mean you go through immigration? And get stamp in your passport? The answer is yes

I have over stayed a couple of times by 1 or 2 days.

It did not cause any problems if I paid the fine.

In fact once they just called a 1 day overstay a mistake and let me through.

I still get my visa renewed without a problem.

As long as through immigration on expiry date

The experiences differ. In my honest opinion, there is not anything right about stamping travelers in or out on any other day than on the exact day the stamp is put. However, people keep saying that they were stamped on the date that was printed on their flight ticket, both in and out. Some are really persistent saying that any other date than the one printed on the ticket is not even remotely possible. Now that is certainly wrong, because many experience exactly that, but the fact that some are so certain of the opposite is a sign that at least there are two ways this could go. Again, I don't understand how; the stamp should always be of the date you're passing immigrations and not any future or past date, but if people experience it, best we can do is anticipate the possibility.

If the checkin desk is open - You need a boarding pass and checked luggage given in. You won’t benefit sitting in the airport unless you are airside.

Yes. If your flight is just pass midnight. Like 00:30 or 1am. Because you need to check in at the counter first then go through immigration on the day of the expiry date. Check in counter only open 3 hrs before the flight.

Don't overstay !!!!!!

It's not the 500 baht fine that is the problem

You have to "leave" the country until 23:59 that day... pass the Immigration until then and you "left" the country... :-)

As long as you go through immigration on the expiry date