This system works fairly well for me:
Leave home with the desired quantity of water in 1L bottles.
I use one Smart Water as primary in the packs side pouch, and one Platypus soft bottle as secondary in the other side pouch if I need more than a liter
2L is usually enough water for a whole day of hiking without crossing water sources. It happens pretty often in the Rockies.
If I need more water for a dry camp, I have the 3L platypus bladder that makes the reservoir of my gravity filter setup (9.5oz total weight). I fill that at a source and carry it along.
On the trail, I fill the bladder, then drain through the filter into the 1L bottles. When those are full, I can fill the 3L bladder and stick it in my pack as a real reservoir. Since the filter is in-line on the drinking tube, if I somehow empty my two 1L bottles, I can drink straight from that, through the filter in a real pinch, or just take a quick break to refill the 1L bottles.
My map and pre-trip recon dictate how much water I carry from source to source.
It's not the lightest possible solution, but it's accurate, easy, and after I had had to make an unexpected dry camp and make it through the night with 10 oz of water, 2lbs of extra water weight is *well* worth carrying all day.
I can easily carry anywhere between 1 and 5 liters and know exactly how much I have, with a maximum 2.5 oz of weight in empty bottles.