You need to decide if you're offering a rental studio, or a fantasy shooting space. In a traditional rental studio, you start with a big empty room. High ceilings, white or neutral walls, smooth floor (concrete, linolium or hardwood) and good access hopefully by a large roll up door or freight elevator. Add a clean restroom, makeup station (or room), changing room, lounging/client area, stereo, kithchenette (fridge, sink, coffeemaker, and microwave at minimum), phone, maybe air conditioning, and lots of power (especially for hot light shooters). Everything else is a luxury which adds to your desirability and for which you can possibly charge: Internet connection, shower, private offices, grip equipment, backgrounds, props, strobe system. In my old studio, we rented it out on a daily basis including everything I just listed (but we had no shower) except for strobes and specialty backgrounds, for which we charged extra. Whatever props or wardrobe happened to be around from previous shoots we would offer on a case-by-case basis. But remember, we were running a full-time commercial studio, and renting to professional photographers who brought their own cameras, lights, stying elements, etc. But that's what a typical professional rental studio is - 4 walls and you bring the creativity. I like a studio with a *minimum* shooting space of about 20'x35', with 14' ceilings. More is better. Our studio had a 25'x40' dedicated shooting space, plus all the extras mentioned above (and our private offices). If you do have your own office in the space, you should consider some method of creating privacy for your renter if you'll be there while they work.
Now there are some fantasy photo shoot facilities - Alan at So Cal Pro models is an excellent example - where they do have multiple rooms settings and shooting bays, all sorts of wardrobe is available, a model referral list, etc, and they rent by the hour or whatever. Although I've never used it, I saw it at one of Rolando's workshops and it seemed like a great facility, but unless you want all of that kind of service, its overkill (although in Alan's case, the cost is very reasonable, and the space is very large). (Note - I don't work for Alan, only met him once).
So which studio do you want to be? Whichever it is, make sure you have liabilty insurance as well as theft for your equipment. Unless you are willing to have your insurance cover your customers (if a model trips and sues, she sues you) then you should require your renters to have a Certificate of Insurance, which names you as a co-insured on their policy, usually for a million dollars. Its not expensive for them, it only cost me $25 when I rent a location and its good until my policy renewal date. You should also think about how much of your equipment you are willing to share (or rent) to your clients. While a "C" stand can take a lot of abuse and is fairly cheap to replace, a camera is neither. Also, remember that maintenance and cleaning is very important, and likely to be more complicated if you have all those rooms and sets to maintain.
One more thing - parking!
Regards,
Andy Pearlman
Andy Pearlman Studio