Help me find the perfect backpack for my travels

http://store.lowepro.com/compuday-photo-250 makes bags for cameras and laptops

http://www.saddlebackleather.com/Shop/Backpacks

Timbuk2 has a http://www.timbuk2.com/tb2/shop/function/camera including 2 backpacks, but I might look into one of their http://www.timbuk2.com/tb2/shop?q=tsa paired with http://www.timbuk2.com/tb2/products/snoop-camera-insert.

Do you want a padded bag? Do you care about fashion vs function? I ask, because I carry the same amount of gear you describe for the same purpose. I bags by https://www.maxpedition.com which are tough as nail but not specifically designed for photo gear. I have always hated "real" photo bags with padded compartments, etc and instead prefer to package my lenses and bodies in individual cases or neoprene covers. Then, I've got a completely modular system. I also don't need or want my camera bag to obviously BE a camera bag, so Maxpedition fits the bill all around.

I've had my eye on http://langly.co/ as a present for someone for a while - laptop compartment (outside accessible pocket though not super TSA friendly), padded DSLR slots, extra pockets, pretty durable and pretty. Water Bottle can fit in the side pockets, not sure about a monopod although you could surely jury-rig something... Also, they were born via kickstarter if that matters as a pro or con for ya.

Oh, I should mention if it isn't clear from the pictures on their site - one of the things I like about those bags is that unlike a typical rucksack - the bag is essentially divided into two portions: on the bottom is the padded gear compartment which is accessible from an outside horizontal zipper that you basically unzip to fold the bag in half and access fairly easily (you can see the canvas that overhangs the zipper in the main pictures of the bag, while the top compartment is a fairly typical rucksack bit with a top access zipper.

I came in to second the timbuk2 backpacks and messenger bags... You may not even need the camera insert, depending. I toss my DSLR, full-size flash, spare batteries, 1-2 lenses and a laptop into a small Timbuk2 commute... I either wrap the lenses in some microfiber and just toss it in, or use the little netting containers on the inside. There are two of them, and you could easily use them for lenses, unless they are huge... The D7100 fits perfectly in it on its back with plenty of room to spare, and I'm sure you could fit a full frame as well. You can carry bottled water on one of the outside side pouches. Not really sure what to do about the monopod, not knowing the dimensions. I have done some professional photo work, and this would be my field kit - but I do it all on a much smaller scale. From what you are telling us, I'm guessing you aren't just using a high quality APS-C lens and a 35mm prime... I'm guessing more full-frame body, and full-frame lenses to match. How big are we talking here? Are we talking good quality prime lenses, or giant 70-200 2.8 zooms? If I was using the beastly giant professional metal lenses, I'd be more concerned with protecting my laptop from the lens than protecting the lens itself.

I've been extremely pleased with my http://www.crumpler.com/ backpack, the Karachi Outpost small, though you'd need a larger one to fit your laptop. I've had it for 5 years and it's still in great shape even though I'm rough with it. All the interior dividers can be removed so you can fit chargers or other cargo, and easily reinstalled. I don't own a monopod but my tripod hangs nicely on the back.

Following on blaneyphoto's suggestion, you might also consider http://www.tripleaughtdesign.com/Equipment/Bags-And-Packs's backpacks.