One more thing to note: If your group is watching material with a lot of movement (sports or action films), viewers sitting at an angle might start to feel queasy. They can mitigate the effect by moving farther away from the TV--the larger the angle, the farther away the viewer should be. Remember this when you set up seats for your Super Bowl party.
Grab Some Glasses
To watch 3D TV programming, you'll need a pair of active-shutter 3D glasses. They're called shutter glasses because they "shutter" in sync to the refresh rate of the TV screen. In other words, each lens alternately darkens over each eye very quickly. While that is happening, the 3D TV displays different perspectives for each eye at the same rate. So the left eye sees one perspective while the right eye's lens is dark, and then the right eye sees another perspective while the left eye's lens is dark.
Now that you know what you're buying, you can see why the glasses are not exactly cheap. Most pairs cost around $150 (LG's glasses are the cheapest, at $130). If you have children (or if you have a small face), you can purchase special kid-size glasses; some are a bit more expensive, but they come in fun colors. If you're a prescription-glasses wearer, you can get some contacts or suck it up--there are no special shutter glasses for you, though Panasonic's glasses (which feature a different design) are slightly more comfortable.
Most kinds of shutter glasses are tied to TVs--Samsung glasses work with Samsung TVs, Sony glasses work with Sony TVs, and so on. That is, of course, unfortunate, because it means that if you own a Samsung 3D TV and your friend owns a Panasonic 3D TV, your friend can't just bring his glasses over to watch 3D TV at your house--you need to have a Samsung pair handy for him.