Since joining AFF I have also signed up at expertflyer and keep an eye on loading.
My travel is all whY or whY plus with 6 returns to the UK a year, four strips to China, and one to the US.
I have been relatively lucky with Op Ups running at about 1 in 6 over the last 18 months or so. I don't expect this to continue though, I benefited from the GFC and reduced passenger loads. (Not sure benefited is the right term! I now fly more and none of it in paid J!!:shock
My success with upgrades using points has been pretty good, 1 in 3, but as others have said it all depends upon passenger loads. It is really a lottery, but being WP gets you "extra tickets" (If that makes sense.)
Since joining AFF I am more inclined to look at international JASA's. If you can plan in advance there are some great deals.
There are many more folk here who will know a lot more but that is my two cents worth. (Exclusive of GST!)
Oh and congrats on getting to WP. You will notice a difference on international journeys. First Class check in and the F lounges are great.