Join their frequent guest membership so you can present the card and look all important when you check in. Dress like you're travelling on business (I'm not saying tie or anything, just a nice golf shirt and slacks) and look like you know what you're doing. Most of the time they won't ask you for ID. Especially if you're paying by credit card.

I'm 23 and remember quite well the BS, quite frankly, that you have to go through. Good luck!