I have used rods from 5&1/2 ft. to 7&1/2 ft. for casting. I have primarily settled on the 7 ft. length as being my all around favorite.
I use either a 4 1/2 or five foot and the thinnest shaft that I can get that still has some back bone. I usually spend all winter walking thru sporting good stores looking for that just right feel. It usually ends up being an IM6 or IM7 shaft.
About 15 years ago I bought a Zebco sportfisher pro guide pgs150 and I thought that it was the best ultralight that I had ever used but it eventually broke and by that time they were discontinued and I could not replace it.... Should have bought ten f them.
Ken