I've had a lot of luck in the past getting both new iPhones and iPads on release day. I got the iPhones from AT&T and usually just got there right around opening time. Near me, the line was short (no more than 15 people). That's one benefit of not living near a densely populated urban area
The iPads I got from Target. At the time, someone came across a link to check inventory online, so I found a couple of stores near me that had them in stock. I remember getting them from a Target in a mall which also had an Apple store. I walked right into the Target, got the iPad, and walked out through the mall and past a line of 30+ people waiting outside an Apple store. I felt sorry for them.
I've been debating whether or not I should drop AT&T for Verizon, but I'm still on an old family plan with unlimited data on two of our phones, so I'll probably just keep it simple and stick with AT&T. If I decide for sure before Friday, I'll probably get up Friday morning and try to get to the AT&T store around 7am. If there's a crazy huge line, I'll just drive back home. You have to decide what your time is worth. For me, getting to a store 1 hour early is cool, but getting there at midnight the night before? No way.