I hear you. I have a Z30 ($130) myself, and while it's a great pack, it's a bit on the small side at 1,900 cubic inches—not quite roomy enough for day-hike gear and a bunch of camera stuff. And camera-specific bags don't allow enough space for sufficient extra clothing and the like.
How about a bigger Gregory? The Serrac 45 ($160) has 2,800 cubic inches of capacity in the medium size, and still has that great Gregory suspension. It's also got water bottle pockets, lots of external attachment points (for a tripod, for instance), provision for an internal water bladder, and more.
Or for the same price, you can get an Osprey Talon 44 ($160). Just a touch less space (2,700 cubic inches) but that's still plenty for gear and camera stuff. Nicely adjustable torso length, and I really like the Osprey suspension; you can load this pack with 30 pounds or more and it will carry comfortably.
Another choice is to just get a small backpacking pack. REI's Flash 65 ($169) has all sorts of internal space (4,000 cubic inches) but it's still very light (3 pounds 2 ounces) and carries great. My hiking partner used one of these this past spring when we hiked part of the Grand Canyon, and loved it. Lots of packing options and an excellent suspension.
Happy shooting! Send us some pictures.