The Story

This very mod is why I started modding. Once upon a time I asked on the Planet Elder Scrolls forums (did I mention it was an awful long time ago?) for a house with employees that do things for me, that look like they are doing things and a place to display / store everything. The most important reply I got was: Your best bet is to make the house yourself.
I started by... butchering is the word, my favourite house mods (typically Korana's) by playing Frankenstein, putting bits of mods together. Needless to say the results were... bad, not only was the game very unstable but I had no idea why things worked in the original mods but not in mine.
More than 10 years later, I've learnt things and Pegasus Estate is almost everything I wanted. It is still in beta but is mostly playable.
I have resurrected an old playlist of showcases a few years old, it shows the estate without the staff. See it all here

Or feast your eyes on all the (old) screenshots.

And now, brace yourself for the full description of... everything!

What to expect:

Quests to become the proud owner of the Estate

• Non-linear Quests to build or improve the house (may require specific staff)
• Non-linear Quests to hire staff and improve their services (may require specific rooms)

Warning: the house is packed with nice features but no loot at all. If you want a money drain, you found it.

Rooms

• Guard Tower: mannequin, view outside
• Mine: soul gem fragments, blue glass, raw glass
• Workshop: handy containers and Morrowind Crafting equipment and hints
• Crypt: master bedroom, bedroom, large cell for cattle, bathroom, Arkana room with handy containers, submerged tunnel to explore
• Orchard: harvestable pears
• Storage: does what it says
• Cottage: storage, minimal NOM facilities
• Garden: grill and water source, variety of plants, river and bridge
• Boat: cabin and storage
• Lobby: many award displayed as you progess (levels, reputation, ranks, Pegasus Awards), hang your cloak up, read about the house and its staff
• Vestibule: many empty shelves to put your best decorations, access to most rooms
• Armoury: labelled containers for all weapons, armour and clothing, mannequin, Pegasus Armour and attire easily equipped and tidied away
• Chapel: choose between an Imperial chapel (with altar), Daedric Shrine, Temple (with shrine) and a Peaceful Place (magic crystal replenishes your magicka for a soul gem)
• Loo: yes, because every house needs one, with flush and all (not the smell)
• Display Hall: display cases, mannequins (movable) and scripted weapon displays, additional carry-able displays, wallscreens and mannequins
• Pool: beautiful indoor pool with waterfalls and a Curing Statue
• Great Hall: grand place with drapes, silverware (not stealable) and music to entertain your guests; quest to throw a party
• Mess Hall: full NOM functionality, scripted bottle display, household coloured candles, set the table and place food on it, cook, bake muffins, pantry containers
• Training Area: working practice dummy, gauntlet with trophies, thief den with lockpick maker, practice doors and poison station
• Lady's Chamber: scripted clothing display, bathroom with scripted bath, scripted tea service, view on the garden, water features, working clock, secret passage, working piano, Morrowind Crafting sewing equipment
• Lord's Suite: mannequins, secret compartment, bathroom, displays, closet, secret passage, pool table and mini-bar
• Guest Rooms (3): very comfortable themed rooms with bathroom and storage for your companions with outside view
• Servants' quarters: nice rooms with en-suite bathrooms to house all your staff who will spend their nights there; see how they like being given extra work at night...
• Study: dwemer inspired room with storage, displays and a scripted writing set, Pegasus related documents sorter
• Library: rotating globe of Tamriel, shelves for all known books and more
• Arboretum: Telvanni inspired room with a sample of every plant
• Syrabane room: Alchemy, Enchanting and Inscription stations, all you need to make items, potions, scrolls, soul gems and sort them in labelled containers
• Summoning room: gives you a summoning spell based on your level
• Menagerie: room that houses both fauna and flora found in the Grazelands
• Pinacotheca: room to display artefacts, statues and paintings

THE STAFF

(will move around the Estate during the day and carry Hold It! items):

• Alchemist: gives you a couple of potions daily, creates the potion sorter
• Enchanter: fills in a soul gem for you daily based on your level, enchant menu
• Mage: gives you a few scrolls or empty soul gems daily, spellmaking menu
• Librarian: sorts and displays books, small quest for a unique piece of equipment
• Agent: helps you find particular NPCs, gives you hints for Pegasus quests, tells you how to find/forge a powerful weapon
• Artist: paints and hangs paintings on the Estate's walls. Helps with the construction of some rooms/features
• Thief: collects trinkets and gems, shares the loot from time to time
• Maid: gives perfume (restore personality), prepares the bath, makes tea
• Housekeeper: adopts cats, sweeps the floor, helps with another quest
• Hairdesser: makes wigs (4 styles in different colours)
• Courtesans: gives massage (restore fatigue), follows you, dances
• Seamstress: make shirts, robes and whole new outfits
• Overseer: leads the crew of builders that build the estate
• Healer: heals / cures / restores daily
• Bard: plays music (duh), may use your own mp3
• Dancer: a ballerina
• Butler: gives you a drink of your choice daily
• Cook: gives you food daily
• Gambler: plays games of riddles and games of three cups, trades Morrowind Trading Cards
• Smith: repairs, gives a hammer daily, makes weapons with blue glass, transforms the Pegasus Sword into the weapon type of your choice
• Herder: breeds and herd guars and a scripted pack guar; guars may be slaughtered for their meat and hide
• Hunter: gives you meat / hides daily, finds creatures for your menagerie, frees the Estate of Cliff Racers
• Fisherman: gives you sea ingredients daily and info on a sea cave with many pearls
• Farmer: plants crops (of your choice) and harvests them
• Necromancer: restores magicka, for a price..., sorts ingredients in the Arkana room
• Gardener: gives you a potted (and growing) plant a day; the plant can be placed where you want and regularly harvested
• Sailor: updates your map with port towns, travel service, will sing for a pint of mead
• Merchant: trades, offers travel services, may be eventually summoned
• Guild Guide: enchants, offer travel services and provides many transport options for you and your companions
• Majordomo: hires staff, keeps track of people in and out the Estate, hints, tidies your keys and sends letters for you, tells the staff to follow their schedule or stay put
• Scout: travel service to the Ashlander camps, companion, picks up plants along the way based on the region you are in
• Guards: Keep the Estate safe, simple companions

Most retainers will give you a useful item or spell in exchange for a gift that is of interest to them.

THE PETS

• Cats and kittens
• Guars and a companion pack guar
• Worg companion

... But also stables for your horse and guars.

THE GEAR

• Pegasus Armour
• Lich robe and hood
• Blue weapons
• Pegasus Weapons
• Working Hourglass
• Amulet to summon the guild guide
• Ring to summon the merchant
• Runestone to travel to any location (including BM and MH)
• Linking scroll to the Estate for you and a companion.
• Various enchanted items, none of them over-powering