Interesting. I just retired 5/15, and haven't even thought in terms of a "dread-free Sunday". Probably because my calendar is full with pent up projects, so I'm just as busy as when I was w*rking. I probably don't feel any kind of major shift because I have been and will be busy with these major projects until the end of the year (bought new car, sold old one, house to be remodelled, etc.). I also have way too many lucrative offers to consult a few hours here and there and the pull is really strong, so that may happen, too.
I suppose I have a sense of freedom now, perhaps even accomplishment, but beyond that nothing major (it is nice getting to go to my favorite coffee place every morning as opposed to only when I had a day off, and it's also nice to not to have to run to the gym in the morning on the way to w*rk).
The biggest thing I've noticed was how much I was tolerating w*rk, just to get to the end. It's reinforced this feeling that I'm probably tolerating living in Southern Calfornia, and will feel much better when I leave in less than 5 years. Never to return.