I live in the high desert of So. Cal. not far from the influence of the San Andreas fault and its offshoots. I use
String Swing wall hangers to hang my solid-body electrics, an Ovation and a lam-body dobro. These are the least susceptible to temp or humidity variables casuing issues. We get shakes, and the guitars wiggle a bit, but the Swing Swings hold them just fine. While it's most secure to hit studs, they don't have to. They come with a nice fat screw-in wall anchor and hold my heaviest axes without a problem.
It's the LACK of humidity here, with typical RH indoors of about 30%, that's a potential threat to solid wood acoustics or hollow body electrics. These I keep in a 'humidor' closet/cabinet arrangement. Maintains a constant 68-72 degree temp and RH at about 45%, with a room humidifier running a couple of hours a nite every other nite. Hit this link here
Home Studio or in my sig to see what I'm describing here.
I also plug soundholes with Kyser LifeGuard humidifiers and f-holes with Dampits, which get a weekly hydration fill. I don't keep anything in cases. These could tend to lock excess humidity in and overhumdify, and I'm a believer in letting wood breathe, not suffocate. It grew in the open air, not in a sealed enclosure. Overhumidification is worse than underhumidification. You can re-hydrate wood, slowly; once the wood has taken on excessive moisture & swelled, you've pretty much got irreparable damage. If you've ever spilled water on a bare wood, unpolished piece of furniture and neglected wiping it up, you know what I'm talking about.
So, to the point of hanging your guitars on walls: solid bodies & lams, should be OK; solid wood hollows that breathe, OK if your room RH is steady at 45-55% and the room temp is 68-72.
Whatever you do, keep any guitar away from heat or a/c ducts and returns. These will blow or suck the life out of anything close.