We're putting in rainheads of some sort in both bathrooms but neither are ceiling mounted. Trust me you want wall mounted ones instead. Wall mounted ones can be mounted at any height. Ours will be around 6'-8" or so as recommended by the manufacturer for a 6' tall person. Anything higher than that and the showerhead is very awkward and forceful....not a soft soothing rain shower like you would want.
Wall mounted gives you the flexibility to go with a different style in the future if rain showers become dated looking or if you find that you don't like the feel of a rain shower head (for example if you have a low water pressure many women find that rain showers don't give them enough pressure to rinse their hair effectively). Having a showerhead from the ceiling is a very modern look which some potential buyers won't like. Having the plumbing routed to the ceiling plus the 1.5' chrome/brushed nickel pipe will cost more than a simple arm for a wall mount. But the biggest kicker is that if you live anywhere that gets to freezing temperatures you can't install a ceiling mounted rainshower on the upper story because your piping will be routing through an unconditioned attic. If the bathroom is not on the upper story and the piping is routed through the ceiling space you still need to be all over your plumber to go above and beyond insulating that pipe or you'll most definitely have condensation around the pipe creating mold on the backside of the drywall. Oh yeah drywall that is another reason you don't want a ceiling mounted showerhead. Most showers have a white drywalled ceiling. With a ceiling mounted showerhead you really need a cement board ceiling with the proper waterproofing and tiled ceiling. A big added expense. You can get away without but it's not a smart idea.
Just to follow up we saved some money by using this Hansgrohe wallbar set:
It's a handshower that is supported like a rainshower. The head is 6" around and has 3 different shower settings. It also has Air injection technology so it can maintain a strong pressure with big droplets and feel like the old 5 gpm shower heads but only use 1.2 gpm. The plumbing, valves, divertors, and fixtures are all cheaper if you can get away with one showerhead/handshower vs. two.
In the master we're going with this exposed wall combo with thermostatic valve which we found to actually be cheaper than buying a separate rainshower and handheld:
We love the vintage look. An added bonus is that it's going to be easier to DIY install than the unit we put in the main bathroom because there is only two pipes coming through the wall to line up. This one also has Air injection technology.