I've been coming here for years, so it's time for an update. Panera is a great place to get to when you want to drink coffee (free refills!) while you suck down some internet and maybe try to get some work done. Quite a lot of tables, many of which do have a power outlet nearby.
The "pick two" is the best way to get a variety of flavors and textures for your meal. Choice of a smaller salad, a reasonable bowl of soup and a half of one of their signature sandwiches. But for breakfast, I prefer the toasted everything bagel (you may want to ask them to put it through twice) with cream cheese is a good meal. Especially since the coffee is refillable.
During the busy lunch times (11 to 1), the wifi will cut out after a half hour. This is your cue to start tethering your phone. Though if the place is filling up, it's not polite to take up a table and not be eating. Give folks a chance. There are also a couple tables outside in the sun that still reach the wifi (but no power).
The kiosk ordering system is great. Skip the line and you can still get your order in and pay. Panera now accepts NFC payments as well from your phone!
Tip: If someone is taking up an entire four seat table by themselves and there is no other space, you're perfectly okay to ask if you can share.