player housing should be in a pocket realm with your choice of environment and house type. i.e dense jungle with a bosmer style house. building should be much like it was in hearthfire, with optional to hire a contractor do do it for you in exchange for gold. it should also be quest driven for certain additions and for gettting the house in general. there should be certain things you can do like...
Trophy room- hire a taxidermist and do daily quests for certain trophy drops or ingredients from dungeon delves/group
dungeons.
Greenhouse-hire gardener to give you quests to collect alchemy ingredients (when upgraded further you could have 1 of each type of alchemy plant)
Farm (exterior extension to house) hire a farmer and do daily quests to collect seeds or gather food ingredients for a reward in special crafting recipes/ingredients for them
Enchanting Room hire a Enchanter to give you dailies to collect special runes that could be turned in for special crafting mats used in enchanting or receive leg mats for enchanting or glyphs (hopefully by then enchanting has evolved to this point)
Rune Crafting Rooom Hire a Rune Mage to do dailies in collecting certain runes for spellcrafting (when they decide to impliment this)
Kitchen- for crafting those yummy foods from the recipes youve collected (have a chart of missing recipes your need for those collectors out there that tell you what the name of the recipe is and the level it is: includes recipes covered by dlcs)
Bedroom- a nice bed to come home to after a long day of questing or conquesting (should have the bed be an activatable that allows your character to climb in bed and have the option to rp sleep or logout)
Library-Hire a librarian to send you on quests to collect valuable texts to display in your library.
Guest Bedrrom- for those that want their friends to stay for a bit. good for rp.
Living Room- a interactable living space for you and your friends to rp in. (interactable chairs plz)
Barn-another exterior extention to your house where you can select a mount or two from your collections tab to fill in your barn. (should allow you to emote your mounts to show your affection and feed them)
Exotic house pet- should allow you to find a exotic pet via a quest to occupy and roam your property/ interior of your house. (should be a generic one for the dlc with options to add more via crown store. should also allow you to show your affection to your pet via emotes i.e. play, pet, fetch: if a dog type or guar, love, etc. pets should be able to show affection back via their generic way i.e. purring for cats, nuzzling for guars, woofing for dogs, etc. these should also apply to any mount housed at your barn)
Shrine-exterior or interior depending on who you venerate. have a quest to fetch a shrine of chosen entity. i.e. any of the 8 devines, deadric princes you venerate, or outside entities like yffre, magnus, shor, syrsbane, etc (the quest should be different for each category i.e. if your getting a shrine for a deadra..the quest npc would be a deadra worshiper)
Vampire/Werewolf chamberr-this would only unlock if your are either a vampire or a werewolf. quest to obtain this from either lamae bal for vampires or hircine for werewolves. (vampire chamber should look similar to a crypt beneath the house. werewolf chamber should be a wooded area via a secret passage.)
War Room- for those that go out and conquest in the name of their alliance. should have things that reflect their rank in pvp and certain trophies unlocked if you achieved emperorship etc.(should include things like a interactable map of cyrodil that updates every hour with your current campaign status. good for also rping for war too)
Other additions could include banners for the skill lines you represent and should be updated when new skill lines come out to reflect your current favor. could also have banners that reflect each of the 5 guilds you currently belong to or the number of guilds you belong to if you have less than 5. also your choice of silverware and style of furniture should be an option...but should mostly reflect the style of house you chose. your friends and guildies should be able to come visit your home if you are party leader and have a group formed. party leader should have their house as priority to prevent issues.
if anyone else has some things to add then feel free. guild hall should be diff and occupy one of the predetermined spots already in the game. will provide my thoughts if desired.