Do you have surround sound? If so, how many channels? If not, why?
Yes. 7.2
Is surround sound something you want (if you don't have it) or something you couldn't live without (if you have it)?
I have watched some old movies before that only have 2 channels of sound and I noticed (as GranteedEV has mentioned before) you really get better imaging with only the fronts playing. Although, if I sat off-axis I'm sure I would feel the center channel provided a better experience. But to answer the question directly: I could definitely live without surround sound.
Do you find much content coming from your surround speakers when watching movies?
It depends on the movie, but in general yes. I use to have my side surrounds on stands at ear level just behind my seating position (I have since wall-mounted them about two feet above ear level) and I noticed much more sound coming from them when they were on the stands even to the point of being distracting at times. I prefer them wall-mounted much more.
If you do have surround sound, did you spring for high quality surrounds or did you go for cheaper ones?
I originally only had a 5.1 setup using the Verus Grand Bookshelves as surrounds, but I felt this was a waste of a good speaker, so I got the Verus Forte Satellites, but they could not handle the DTS 5.1 intro without distress so I moved the VGB's from 2 channel duty back to surround duty and put the VFS's on the back wall for 7 channel. I still feel the VGB's are wasted as surrounds, because they're great when showcased, but I've been getting into the DIY side of speakers for 2 channel so I don't feel so bad about having what I consider great 2 channel speakers playing a background role.
If you went cheaper on the surrounds, have you ever heard a system with expensive surround speakers? If so what brand? Did you notice any differences positive or negative?
I have never heard a system with more expensive surrounds. My theater is the best I have ever heard, although I don't get out much.
I tried to go cheaper, but it didn't work for me as I like to play some things at reference level and the little 4.25" coaxials almost gave up the ghost trying to keep up.
At what level do you usually watch movies and what is the noise floor of your room?
-7.5db is about where I listen to most blu-rays, -32.5db is my standard TV level, -12.5db for music. I'll turn it up to 0db if I'm watching The Dark Knight Rises or the like. The noise floor in my house is much higher during the day, but at night it is fairly quiet. I have never measured the noise floor to give an exact number.