First off, I am a rod junkie! But another thing to consider is canoe fishing. I have a few rods that are shorter to be used while canoeing. Now, these shorter rods are not puny, little noodle rods. They are short but contain a fast or xtra fast action. My preferred one is the 5'9" St. Croix Avid. In addition, I will usually carry two more rods that measure 6 foot or maybe 6'3".
Now, If I was fishing larger rivers, where longer casts are ideal, then 6'6" or the seven footer is added to my arsenal.
Many anglers say fishing rods are like shoes, you can never have too many!