What should I look for in a GPS?

I am looking to buy a GPS system but don't know a lot about them. What I do know is that I want a wide screen, I want to be able to chose from various routes, I want lots of POI, I want voice commands as well as text directions, I want to be able to view gas prices and real time traffic, I want no monthly fees or update fees and I would prefer if it was under $200! Are there any other features I should look for or make sure they don't have? What brands are the best? Is there a website where I can find comparisons of all the brands and the top GPS systems as well as the pros and cons? What does it mean if it has or doesn't have a car locator?