I use for Spa Sisters a modified pony body model and i first use another technique for hairs and modeling the mane
If you need a smaller picture, you can take a look on my backup page, where several resolutions are [link]
Modelling and adjusting hairs and colorized takes a week or two (i don't remember exactly). Render time was less than 12 hours i guess
I serious was a little bit afraid — because Spa is the pure force to be beauty. But as longer i look to my output as more i guess i didn't miss my target to make a beauty picture
so i hope you like it too
BTW: If you really like it — i would make a big picture of both Spa — amazing high resolutions for printing on skycrapers