Well, my hair's not super long but I think mostly up is better than down for the ends.  There are certain fabrics that stress the hair when it is down-anything the hair sticks to.
Still, you have to be gentle with what you use to put your hair up.  No metal, hairfriendly elastics, no metal barrets etc will help.

Good Luck, I'm sure the others here will have much more advice for you!

lol @ Sasha's cat  That's cute.

I've been wondering this same thing, because it may be possible that wearing my hair up all the time has caused mucho breakage. I may be wrong about this, of course.

Would a single braid be better? Oy vey, I wish I had a hair servant to braid mine for me every morning...that would be just heavenly! 

BTW, Sasha, what do you use to make your hair smell like roses? I am so envious! 

In general, updos and braided styles are considered protective. If hair is in good condition, wearing it down every now and then shouldn't cause troubles. Coarse hair seems to tolerate wearing down more than fine hair. But as long hair that is left loose tangles easily gets caught in things and rubs against fabrics, chair backs etc, and needs to be detangled and handled more, it inevitably causes more stress to hair than an updo would. Especially ends are fragile, and they can be protected well with updos.
   Updos can be damaging too though, if hair is pulled too tightly or if you secure it with bad hairtoys (for example: elastics that have metal parts, hairtoys with sharp edges or seams etc). Many think that it's beneficial to wear different styles that are secured differently so that one spot isn't getting all the damage from possibly damaging toys etc. Angel Spun, could something like this be contributing to breakage you're experiencing?
    Another thing is, that it seems that many people find that living with very long hair is easier if it's kept up most of the time.

My hair isn't super long, but I wear it almost always contained in an updo or braid. The few times I've worn it down I've felt that the hair is everywhere. As my hair type is fine, I doubt that if I wore it down constantly, I would be able to reach my goal.

One thing to remember if you keep your hair up all the time -- don't pull the buns or braids too tightly.