As I sit here answering this, I gaze at my desk, grab the tape measure, note that my desk is 5' wide, and say... 'Damn!'
For me that's too big, but this is all personal preference- if you do it and its comfortable, then cool. How big of a monitor are you planning on using? If its not wide enough for everyone to see well, then it'll need to be moved back, do you have enough room for that?
Maybe dig around for some dimensions on some of the popular 4player games, maybe a Simpsons or one of the newer basketball games- my geuss is gonna be around 3' edge to edge
For shoulder room, figure about 1' to 1-1/2' per person, but remember that most of the big games have a curved front edge, so the controls may be only 6-10" between players(this is close to my 3' geuss)
for the record- Ive got 2 players (p1+4 buttons, p2+2 buttons and a centered spinner) fitting into 23-3/4"