Here's what I use for day trips:
Arc'Teryx Miura 30 with a custom insert made from left-over Think Tank bits
I have two versions, a stripped down one and a heavy-use one:
Light version fits: 1DII, 70-200/2.8, 17-40/4, 1.4x, filters, cards, remote, extra battery
Heavy version takes: 2x 1DII, 70-200/2.8, 24-70/2.8, 17-40/4, 1.4x, filters, cards, remote, extra batteries
Inside the backpack, I also usually pack a small stove, pot, canister of fuel, down jacket, extra gloves, extra hat, extra socks, headlamp, knife, compass, snacks, water bladder or bottle(s) and emergency / first aid kit.
I attached a lot of extra straps to the outside of the pack, and can easily affix all of the following (at the same time): crampons, ice axe(s), snowshoes, tripod or monopod, pad for sitting / kneeling on, extra clothing if needed, rope, helmet, etc. If needed, I can even strap a tent and sleeping bag & pad to the outside, making it an overnight pack.
All told, it weighs a fair bit. But the suspension is comfortable for full-day trips (think 4 am start and 11 pm return) and fits all the gear I would need for a day out in the mountains. Keep in mind I don't usually need any additional clothes except a down / synthetic jacket for rest stops and extra gloves / hats and a pair of socks in case I get too sweaty.
For longer trips, I reconfigure the inserts to fit into my other backpacks. I have yet to find a commercial solution that would do what I need it to. I am considering a custom-made pack from Dan McHale in Seattle, designed for my needs and fitted to my body. But it's an expensive option ($800+) and requires a trip to Seattle.