This is a much often asked question. I did a search using "couples" as the search word. The link is to just one of numerous threads on couples. Many providers enjoy entertaining couples. Many escorts will request to speak with your s/o before the date and many suggest that the s/o actually pick the provider you decide to see.

Definitely hook up with one of the hotties here on TER that has experience in this...

I'm sure there is a lady or two on this board who you can take care of in advance to make it seem completely spontaneous and your SO would not even know they were being "hired" to make your Vegas Experience something both of you will never forget.

Cheers!

don't force it, let it happen naturally

OK in dealing w/ couples where their ladies is bi or bi curious let me just give my 2 cents.I have alot of Guys contacting me about this situation. More than half the time they cancell because she gets presured or mad/pissed and they have to back out which makes me mad because I could have put someone else in that slot that really wanted to see me that nite.
  If you push the subject you will push her farther away...a bi/bi curious woman needs to find and figure that side of her sexuality on her own,seriously and dose want want a dude hovering over her shoulder.....Been there done that. If you just want a 3 some i would just hire out another professional provider couple to see for that sexual satifaction it seems like you maybe looking for.

my 2 cents...xo Jenny Syn

Like in my daydreams bi? tipsy and kiss a girl bi? was bi in college?

Similar to Jenny I get quite a few gentleman that are interested in setting up a
sensual couples massage experience but haven't quite flushed out the details with their
partner.
The KEY to this working for women and you getting the experience you want is
her comfort level. It won't be sleazy or disgusting of you make it about having fun with her.

"Jane, we should get into some trouble when we go to Vegas this trip. Any ideas?) (big grin)
wait for her answer. you say>>>
We should
-see how many strangers we can flirt with
-have a clown come over
-I've always wanted to be with 2 women.
It would turn me on to be AROUND you and another hot girl.
What if we called someone over to JUST hang out with us?

*** In my experience, even with shy women- One cocktail, 2 hot women and no pressure you will
get all the FIREWORKS you're looking for but you need the go ahead from her to invite a provider or
massage person over.***

You'll be able to gauge her reaction and see which way you should go. My advice would be different if
this were your SO but this way you'll at least get it out there.

Feel free to PM me if I can make any of this clearer.
-  Rose

QUOTE "..She is bi. We have batted around the idea of a threesome, but we haven't really fleshed out the details.....
...Two questions: Should I just try my luck at a local club or make arrangements with one of the ladies on the board? .....,
..... how do I broach the subject of calling an escort? I am not sure how she'd feel about "hiring" someone. Would she be disgusted? Would she think I am a total perv (Well, I am, but...). "

Answer to Your questions - Hire a Pro - to explain this to your FWB gal, say
You want to keep the two of you safe and clean, NSA, so you have done a bit of research on escorts/ brothels- your findings being that in most cases, Pros are less risk for std , psychos, etc!-  safer than picking up a girl at a bar or club, and, usually a Sure thing!  As for the hire/pay part, just say to your gal that You have No problem spending money to hire a professional to keep you and her safe.  She most likely will respect the fact that you are looking out for her safety as well .
This way, you both have fun, and then its over until you hire again.
Answer to your Second question, IMO, She won't think you are a Perv if the two of you have already discussed having a threesome, and she sees you as an average normal male! If she does think you're a perv , remind her " We had discussed a threesome, and if it would bring you pleasure, then I want to do it and I would enjoy seeing you with another woman ! I of course want to make sure she is NSA, safe and clean. I feel professional is better especially for our first encounter! "
This is all assuming, as your wrote, that she really is Bi, and is interested in a threesome. If she is Not totally into it yet, Don't push it. Let HER be in charge- and included in the selection process!  Ah, and there is another good point! Tell her by hiring a Pro, the two of you can learn a lot more about the pro before the date! The two of you together could spend an evening looking at websites, reading reviews on gals that have met with couples, gals that are truly bi, and let Your gal pick her favorites,...have some fun while doing your research together xoxoxo
Hire a Pro, and Let your Woman be involved in the selection, When she is ready, and all should go well  HAVE FUN!