I am a woman,planning to go to Las Vegas before the end of July. I am also planning to set some time aside and have an escort/GFE for myself. I was looking around the TER website and couldn't find a way to sort women n terms of me looking for a brunette not a blonde.

You'll find it in the "provider's appearance" section.  Of course if you are a VIP, you can enhance your search capabilities, and identify ladies who are really bi.

Good Luck, and if you get lucky, write a review,

jazz32

Many do not!!  Her site should indicate that she welcomes women or that she is "bi"