I think the appearance of a studio should reflect the functions you require of it, with minimal extra distractions.
Depends on what mediums you are working in, but since you say ‘office’, I assume you’re not talking about a full fledged model shop.
A large amount of desk space is great, especially if you can discipline yourself not to use it for storage
. That way you can have a ‘project area’ that you can reconfigure at will. Doesn’t have to be a desk, a sturdy table works even better, imho.
Varied seating options. I don’t buy in to the $6000 Cyber-Aero-Nano office chair hype, a good stool and a few other chairs work fine. If you have visitors, you have seating, and if you’re working for hours on end, you don’t get cramped by sitting in one place.
Good ventilation, at the very least a portable fan. Can’t overstate how important fresh air is after working in one place for hours on end.
Ample bookshelf/storage space. Don’t let stuff you’re not actively using crawl out in to your precious work space. Something with goodly sized drawers or shelves is best. I have found this a useful general rule when dealing with furniture: larger ones can always be subdivided, but not vice versa. Make it sturdy.
Window shades or even a curtain if direct sun or exterior noise/activity is a distraction.
Good lighting. Light spread out around a room works better than a few point sources for ambient. Get a strong, wide focus task light for finer detail work.
Good stereo or speakers. You need something to keep you company while you work.
Bulletin board. I don’t have one now, but I used to use one.