I have the Adventure 9. I can fit my D50 with 18-135mm lens attached, 70-300mm VR lens, 90mm f/2.8 Tamron, 30mm f/1.4 Sigma, Nikon 50mm f/1.8, SB-600 Speedlight and Gary Fong Lightsphere II diffuser. In the top part I can fit my Sony Digital8 Video camera, a few extra tapes and the cord to charge the battery. In the side pockets I have the battery charger for the D50 battery on one side and a gorilla pod on the other side. I also keep 3 extra batteries, 2 filters, 8 (or so) SD cards and a few other small things in the front inside pocket.
On top of all that it holds our laptop and I can also fit with the Video camera a portable hard drive with cord and the power cord for the laptop.
All that being said,,,, it sucks when you carry it on your back. I'm 6' 280lbs and it is HEAVY. I don't carry all that around parks. I just use it to keep all my camera gear together in one place and also for traveling (once I get to my destination the laptop comes out along with all the cords, HD and video camera.