I would have a library with one of those ladders to slide around the room on.
Yep ^ I'd be sliding around the room like Belle!
I'd have a gorgeous armchair/snuggle chair to sit and read on in a little reading nook tucked out of the way. Plants everywhere and good quality, soft lighting. A projector would come down with the press of a button and enclose me in a little personal cinema, and in the wall next to the chair there would be a fridge and cupboard with wine, popcorn, and chocolate.
There would also be a writers' nook embedded into another wall, with expensive fountain pens and notepads, a beautiful desk, and speakers playing inspirational music (quietly because it's a library!). There would also be a massive computer screen behind the desk which is treated as a piece of artwork unless I need it for research.
Since money is no object, underneath the thick pile rug in the centre of the room the floor would retract and there would be a hot tub built into the floor. When the floor retracts, the bookcases would be covered with a protective screen which acts as a giant tv/projector with a choice of nature views, so I could be in the middle of the mountains, or at the beach, anywhere! The appropriate sounds would automatically play. Oh and behind one of the bookcases would be a sauna with a selection of whitecompany robes waiting for me, just because I can!