Before you buy a cabinet style make sure you check out Spicewine Ironworks. I don't own one...yet, but I have the (mis)fortune of driving past their shop everyday on the way work. They build some great units and it's just a matter of time before one is on my back patio. By the way, I've cooked for close to 40 people on 2 Weber Smokey Mountain cookers. They're about $300 each or you can get the 22.5 inch for about $400. That cooker is really big enough for 25 people. Like someone esle said, add a Guru or a Stoker (what I use) and you're set.
Joe -- 22" Weber Kettle(2), Smokey Joe, Baby Q gasser, 18" WSM (2), Stoker