One thing I know from experience is that you absolutely CANNOT stack them flat - one on top of another for any length of time. Maybe a record or two sitting on top of the turntable for a day or two, but that's it. I lost a mint original copy of the Stones' "Let It Bleed" that way. Haven't done it since.
I'm glad the OP put this up because it's making me think about my own collection. I have them on on Ikea shelf in the bedroom, but it gets a bit humid in there (I live in a 1st-floor apartment set into the foundation - in northern CT). That's the only real issue here. It doesn't really get hot enough for an air conditioner in the summer, but it gets cold in the winter. I have a woodstove coming (Have to make an adaptor for my fireplace - My brother is a volunteer fireman, and he's going to help me with that - He's a bit of a workaholic though, so it's hard to pin him down sometimes - Anyway, that's for another session), and once the stove is in, I'll be able to keep the bedroom door open and heat the whole house rather than closing off the living room area and heating that, and hopefully that will cure the moisture problem (in the wintertime, at least) - I still may have to keep them in the living room in the summer though. Moisture has been an issue since I moved into this place, but thankfully no overheating.
I prefer living up north. Sure, the winters are tough, but I could never live in the deep south. No way. There are too-many things that can kill you down there. Plus, I'm incredibly-terrified of large spiders (and a few other bug-like creatures that you encounter in southern states. Some people hate snakes, birds, bees (Well, actually I'm allergic to those so I have a good reason to be cautious around them), and plus there are those who hate cramped areas, dirt, or Virgos. My phobia is spiders. And I've spent many years in my younger days (I'm 39) down in Atlanta with my father while he was living down there in the '80's/early '90's (I'm from a "broken home"

), and I have many relatives in Georgia, Florida, and a few other states down south, and I've seen way-too-many things down there that make me nervous (not to mention the alligators, crocodiles, and all kinds of deadly stuff. I saw a video on YouTube not that long ago where some guy was filming this pair of gargantuan spiders living in his garage (One was a female with a big egg-sack on her back). The eggs eventually hatched and she ate the male (I honestly can't remember which happened first), and THEN the homeowner got it into a box and brought it outside, freeing it a little ways down the street. The worst part was when they put the box on the ground to free the spider, they realize that there are a bunch of equally-big spiders all around them on the ground while they are filming this. Now, I'm sorry but that stuff freaks me the hell out. Not for me. I will NEVER, EVER live down south. Ever. Maybe a quick visit once in a while because there's a lot of cool sh*t down there, but no extended stays. I can't handle it. I've tried.