Getting the saddle right is the first bit but I find this much easier than fine tuning the bars. My best method so far has been to get the tops and hoods right, especially the angle of my wrists when on the hoods which the height of the bars influences. I would do this with any bars you have and then see how the drops position is. If it's not right then it's a case of trying to imagine what shape of drop would fit the bill, the links provided would help in this. I also pay attention to the flare, or lack thereof, in the drop part, slightly out suits me better. I've tried a few bars and didn't like the anatomic ones at all, shallow drop seems to work best for me, I have two sets of the FSA Vero Compact now.
Interesting on the shoulders, I do try to conciously follow Sheldons advice to try and round the back rather than allow the upper body to slump between the shoulder blades, not always successfully though.
Just on the saddle height, I think mine was right for how I used to ride but when I got another road bike a few years back my style began to change. I transformed from a big gear masher constantly riding on the rivet to a higher cadence more relaxed style and this has put me in a more upright position and because I'm not pushing so hard my seat height has come down slightly (I'm a toes down pedaler). Anyway I think it needs to come down a bit more but this isn't going to alter my bar selection much.
Also I think I've got some posture problems I need to sort out seperate to the bike, too much sitting on the couch with laptop and dog, so I'm not going to overly worry about the knotted shoulders just now and see if changing the bars helps that anyway.
Back later with some measurements and piccies for perusal.