Here is a four footer that I created for my nephews about 7 years ago.
IIRC, it was comfortable sitting on a small bench and playing. The control panel is about 27-28 inches off the ground.
There was so much more I wanted to do to this cabinet, but I rushed it to finish for Christmas 2005 and haven't seen it since.
Hope it gives you some ideas in regards to size.
I like the look of #2, but if you are sitting down, I don't think I'd like the viewing angle since it looks to be set up for looking down at it. Although, I think it would depend upon the height of the chair you plan to use. Create a mock up of the height of the monitor and angle and see how it looks sitting down on your planned chair.