Watch out if you're looking at OLED TVs, they can exhibit signs of burn-in within a few months.
If you're truly mixing media then it shouldn't be an issue but if, for example, you're watching a lot of ESPN, which just about always has a news crawl at the bottom, then it's pretty much inevitable.
The manufacturers are saying this isn't so, but they're not testing under the right circumstances. We're testing out new OLED Displays at work and for folks that constantly have static images on their screens, like for example a specific spreadsheet they use all the time, the burn in is definitely happening.