I've been meaning to write this post for a long time. This is how I finally decided to rig up my camera and my day pack. I didn't want to just wear the shoulder strap around my neck for obvious (discomfort) reasons and I didn't want to store it in the main pack which would require me to stop to get it out for photos.
There are LOTS of different systems/straps to use. Since I wasn't sure what I'd like or what would work, I didn't want to try something expensive. After a lot searching, I found a really inexpensive solution to try.
I ordered this set of straps from Amazon, it's under 10 bucks!:
The straps clip onto part of my shoulder straps (and I suppose it wouldn't work with all daypacks depending on the width of the straps). The bottom half connects to my 7D. Now the weight of the camera is on my shoulders rather than my neck.
Since I removed my original camera strap, I needed another option for when I was carrying my camera without my daypack. So I ordered another OP/TECH strap: OP/TECH USA Utility Strap - Sling (Black)
This strap is an inexpensive (less than $25) strap similar to the Black Rapid that's around $60. The Black Rapid attaches to the tripod connection, while the OP/TECH uses the regular strap connection point. Since I like to wear the camera on my left hip in this setup (lefty!) some things don't work as smoothly as it might on the right hip, but if the strap gets in the way, I just disconnect it while in use.
Since this strap comes with 2 different connections I had a spare that I could connect to my small G12 (actually, I didn't need either of the camera side straps since I'd purchased the ones for the daypack setup). The G12 is light enough that I wouldn't need to use both strap connections, but I do connect to one of the straps. I worried it might bounce around too much, but I used it this was for the whole Panorama/Mist trail hike in Yosemite and it never bothered me.
I haven't used the 7D in daypack set up for long hikes yet, but I did use it at Point Lobos and various other short hikes in California and at home.