I had an idea that Dev’s may not have thought of for Guild Housing. It would probably be easy to do and would likely make Roleplaying Realms happy too.
The idea is to spruce up the old Original Karazhan so it looks neat and tidy remove skeletons on beds and NPC’s and such and put it in it’s own phase. Then give access to the guilds as guild housing.
There have been a number of threads over the years asking for guild halls. The current thread regarding the guild permissions also has a number of posts on the topic. The new Guild UI and Permissions...yikes
For a long time, players have liked this idea. Maybe your post will give it some more traction, OP. Fingers crossed! 
In order to avoid garrison troubles - there could be a few dedicated guild chosen rooms that are instanced to that guild tag.
The rest of the place a common area for all guilds, with a dedicated space there. Unguilded could also have a specific area of access for recruitment.
I believe Blizzard’s statement on guild housing was: “Guild housing sounds fun for the guild master, but unfortunately not so much for everyone else.”
It would make guilds become a commodity like they were in Cataclysm. Sell a guild with a fully upgraded Kara tower, make major bank while screwing over everyone else.
The problem is to figure out how to make guild housing not turn out like guild perks. Guild housing sounds on paper until it comes time to figure out to get them to work.
Swtor has it.
im woried about being in a house with my guild mates…
theres a few of them that dont know how to clean.
Legit theyve sent me horror pictures of sinks.
I saw some incredibly elaborate guild halls in guild wars 2, and they were empty. They really had no features that could compete with a city and no reason for a player to go to one and stay in it for any length of time. Simply they were a toy for the GM to decorate.
There has to be practical value to a guild hall that would make a guildie want to go to it multiple times over his/her play session.
It also needs to be something everyone can influence, otherwise if it’s just the gm and his cliche of friends it’ll be a source of guild drama.