As for towering sunflowers, I love them.
Um... about quadruple that size is no longer "fun"... it's downright scarry to stand near them! BTW, the variety in that pic doesn't look like the mammoth's that I planted last year. They were single bloom plants. The blooms were nearly 3ft diameter and heavy as all get out... too bad I didn't get to harvest the seeds from them... they all went to rot before they were ready to be pulled out... but the birds still enjoyed them.