I'm a big believer in a "spatchcock" turkey (removing its backbone). It makes things much more manageable on Thanksgiving day. Takes up less oven space, cooks evenly, remains very juicy and takes way less time to roast.
Here is a link to Mark Bittman's method and video from nytcooking.com that explains how to spatchcock.
How to tell if it's done ~
A thermometer should reach an internal temperature of 165F in the thickest part of the breast meat and 180F nearest the bone in the leg meat. If you don't have a thermometer no worries. Here are other signs that your turkey is done:
For more tips check out Karl's tips here.