Nice Bill. I have not grown the large type flowers for a few years because I enjoy cutting flowers and bringing them to the office and giving bouquets to friends - also the smaller flowers bloom successively over a period of many weeks as you deadhead each batch of new flowers. The seeds on the smaller varieties are not as good for people either - too small to eat - but it never stops the birds and squirrels.
I need to get a tape measure and see how tall some of my plants have gotten - pretty sure they are higher than 10 feet - I have played a fair amount of hoop in my day and they are definately higher than that.
Yes the stalks can get pretty substantial too. It takes me a few hours once the season is over to cut them up into small sections so that I can rototill them into my garden.