You may have heard of Emma, she is the creator of many wonderful Morrowind and Oblivion mods including Companion Vilja. She has posted a topic at BGS Forums called Looking for Companion Friendly Houses, it contains a list of companion friendly houses and information on how to create them.
The basic requirements are:
* Pathgridding - very important for the companion to be able to navigate.
* Unowned beds & chairs - so companions can sleep and sit down, they won't do so if these have an owner.
I want Guild Benefits to be companion friendly, after all you own your bedroom in the guild halls so your companion should be able to stay there with you. However, there was a problem... three of my rooms were accessible to other NPCs who decided they would like to use my "unowned" chairs and beds themselves. We don't want strangers in our bedrooms, this just won't do! Thankfully PrincessStomper had a suggestion, make the furniture owned by the PlayerFaction since companions belong to the PlayerFaction they should be able to use them while keeping other NPCs from doing so. Guess what? It worked!
Advanced requirements for public & semi-public places:
* Furniture owned by PlayerFaction (for use by player and companions only)
Last night I went around to all of my beds and furniture (and my food items just to be sure) changing them to owned by PlayerFaction. I went in game to spy on the worst offender, Contumelorius Florius in Chorrol. I took all the food from his room and the rest of the basement, leaving only the PlayerFaction owned food in my room. Then waited for him to come downstairs for supper. He went to his room looking for food, finding none he walked out toward my bedroom door. He stopped just outside, then turned around and went back into his and just stood there like a dummy. It was so funny to watch!