I like arriving at the tents late afternoon after eating a big mid-afternoon meal. By then you will see many people being (literally) carted off who forgot to eat. I like the Lowenbrau tent, but different people have different preferences. The whole place is awash in tourists and the Mecca for most tourists is the Hofbrauhaus tent so it's my least favorite.
The hats are a good souvenir. Similar to buying kilts in Scotland, the price for a good quality hat is approximately one arm and part of a leg. Since it is likely to get lost or soaked with beer, a cheaper version may work fine for your purposes. You can get a better price at Busch Gardens in Williamsburg than you will see in Munich.
For the neo-traditional look, wear one of the hats, a beer themed t-shirt, wide suspenders, cargo shorts and the tall traditional socks with either walking shoes or hiking boots. You can probably only pull off the look if your German has the heavy Bavarian accent (I liken it to our Southern accents). I saw numerous young men sporting that look but didn't attempt to copy, I just wore casual clothes.
