There's no difference in the packaging of the GTI and the Golf, but the tight back seat of the base Golf doesn't worry enthusiasts so much in the three-door GTI.
In front, the 2011 VW GTI fits enthusiastic drivers very well. The GTI comes with standard sport front seats; they're bolstered thickly and they can be adjusted in eight ways. We do wish the adjusters could be simplified--it takes two levers and one big knob to set your ideal driving position--but once you're there, the GTI has hours-long comfort in its chairs, and excellent forward visibility from behind its somewhat tall dash.
Tall drivers in the front seats will cut down on the legroom available to those in back, where knee room can become an issue. It's difficult to get into the back seats in the first place on three-door models. There's an "easy entry" seatbelt holder on those three-door models, but frankly it doesn't make clambering in back that much easier. Once you're settled in back, shoulder room and head room are quite good, and the rear seats get adjustable headrests and a fold-down armrest.
The rear seats also fold flat to open up the 15-cubic-foot cargo area, revealing a bin of a considerable size.