Hey Javeryh,
Another thing I'd highly suggest is to come up with a list of everything that you really want in the basement. Measure that stuff and keep little templates (I did this in excel). Then copy and paste them into your designs a la colorforms and you'll really start to imagine how the place will feel.
Also, think about creating separate design plans. One could be for lighting (lighting placement, switches, dimmers, which switch controls which lights?, etc.) another design for sound (speaker placement, receiver placement, in-wall controls, touch screen, etc.) and even another separate design for TVs/Screens (placement, outlets, coax cable, HDMI cable, receiver, receiver placement, etc.)
That stuff will really help you flush out some wants vs. needs as well as help you measure quantities such as wires, lights, speakers, screens, etc.
One last thought for now...our biggest decision for our basement was whether to add a bathroom or not. Initially we weren't going to, but we are very happy that we did. It's a little getaway and going 'upstairs' to use the restroom would be a big buzz kill.
-HanoiBoi