Tomato Spacing

Meesh here. Hi. I'm taking a poll... how far apart do you plant your tomato plants? There's been some discussion 'round here whether it should be 2 ft or 3 ft. Wondering what peoples' thoughts were. Please comment. And here's something new I learned about transplanting tomatoes... plant them deep so they root stronger. I had learned that when transplanting (in general) ya put the start plug in the ground so that the surface of the plug soil is level with the surface of the ground soil and not to get any new soil packed up around the stem of the plant. Well, I guess with tomatoes it's different. We have tomato starts that are about two feet tall, they're now planted in the ground with just about 6 inches of the plant above ground. All the stems underground will take root making the plant stronger. Any comments?