I am not sure I would want to do my 40s over again. With most of my children grown and gone onto their own lives and having grandkids and more free time I am pretty happy where I am atm.
I love to travel and it is easier now that I am older. I find that my age (though not quite senior) does allow me some nice discounts.
I think I am pretty happy here in my 50s. Share some of your pro's and con's for this time of our lives.