For more than one person or cruising purposes a side by side starts making more sense. Quads are hard to beat in terms of versatility (not to mention FUN factor). They will also go alot of places a side by side can not think about going. I've had my boys on quads since they were 4 (now 11 and 12) and we've had more fun together than is even measurable.
Aside from that, when I get the chance to get out with my buds I grew up on the track with we get the chance to act stupid like we did in our glory days. We traded doubles and table tops and whoops for big hill climbs and fast trails. Life is all about compromises when ya start havin kids
I've driven friends side by sides enough to know no doubt someday I'll at least own a side by side but at the moment the full sized UTV's are just too big and too wide for what I like to do. It just comes down to personal preference.
800cc Vtwin, 2x4/4x4 on the fly, tri mode power steering, flexx handle bars, bead lock wheels, Fox Podium 3 way shocks with remote resevoirs, cammed, chipped, piped, upgraded throttlebody, aftermarket primary clutch with a tweaked secondary for optimum back shifts.
She's just a big bag of fun :-laf