Workshop/office. Size of single car garage would be ideal. Can be in basement, detached garage/studio, or attached to house on main floor. Room used for bicycle storage & repair, working from home. Need counters to work on and storage for bike parts, clothing, and other non-motorized hobbies and crafts. Need empty open floor space but maybe not as much as the photo. This is not a garage full of ladders and power tools and junk storage. Office area large enough for desk/Standup treadmill, filecabinets and sloping drawing desk large enough for blueprints. Room for weights for working out, bike trainer. Ideal with wetbar and music system.
Modern window treatment doesn't take away from Spanish feel. Bump outs and low sloping roof, tall tower for fireplace / kitchen exhaust helps break monotonous roofline. If this house was on our property, this view would be from the south east. The yard area would need to be shallower, about 20 window to the right could be laundry room and it could bump out, creating a bit more courtyard feel.
I like idea of barn door or fabric hiding TV, speakers, wires etc. If ceiling high enough, a low gas firepit could be below the TV? In one floorplan I worked out, I had a family/TV room to the west of kitchen with a covered porch area to the west of the TV room. The TV would be on the west facing wall. To either side of the TV/firepit wall would be glass doors 6' wide each. The wind blows from the south west, so these doors could slide into the wall so wind doesn't destroy them. On the other side of the glass doors is a covered patio. Maybe the main entry comes into house with option to turn left into this room or right, into an area leading to kitchen / dining / reading nook.