and make sure she is included. WOW!

From a providers perspective....

I only do 3somes with women I LIKE to fuck. If one is not bi then it is not going to happen. I have done them with some that are "curious" and I ended up just fucking them the enitire time. Well now I have learned my lesson on that! lol A 3some should be all involved going at it IMO You can usually read the reviews to find out if the women are into each other.  
Here is an example of what I am talking about
Hope this helps and hope you find 2 that will rock your world
Hugs and kisses
TL

I provide the best VIP Duos with my identical twin!

We already love each other!  lol

I know several wonderful providers who . . . wait for it . . . actually have SEX WITH EACH OTHER.  No they don't watch while the other one participates, they don't suddenly disappear to the bathroom while the other is getting it on, and they don't lightly caress each other's backs and blow air kisses at each other.  These girls know that for at least that category of men in which I place myself a 3some means everyone fucks everyone else.  Otherwise might as well have the two ladies visit you back to back.

As for recommendations--ask and ask again.  Once you've gotten through the screening the lady should be willing and able to answer some frank questions.  Don't ask whether she's "bi"; that's conclusory and doesn't mean shit anyway.  Tell her you want to see DFK, DATY and whatever else your little heart desires between the two ladies and that if she and her friend are not 100% into that then you'd be happy to see them separately.  Another good idea is to ask one of your regular ladies--if you are comfortable with each other a conversation about what you really want in a 3some should be easy to have.  I've had some of the best 3somes with ladies I'd seen several times alone but who was willing to bring a friend or who--in an act of generosity that may be hard to find--was willing to actually recommend another lady.  And read the reviews--lots of girls have been given the "really bi" designator but when you read the text of the review nothing happened between the ladies.  And listen to that voice in your head--I've had ladies say "oh yeah I do all that stuff" or words to that effect and it almost always means she's shining me on.  The code words may be different in your case but trust your instincts when you think you're being bullshitted.

"Maybe porno has ruined my expectations . . ?" Answer: Porn Chix! Done a number of 3-ways . . .

most of which have been with adult film actresses and the ones with them have ranged from wonderful to the three best sexual experiences of my life! (Those being with Nikita Denise & Claire Dames; Nikita Denise & Alexandra Quinn and Nikita Denise and Kiki Daire) There's an obvious underlying commonality there (ND is truly in a class by herself) but as other posters have hit on another key component to this: getting two girls who really like each other, are comfortable with the other and genuinely enjoy playing together.  If you get that, you should have a great time.  Of course, if you have one or both of the girls who are genuinely bi, jackpot!  Another amazing threesome was also with ND and a non-porn girl who was clearly TOTALLY into Nikita and that vibe added to the thing immensely

I also note that you're in the Northeast and would direct your attention to Queeny Luv as a close and fiscally attractive option.  While I have not had the pleasure of a three way with this sweetheart (which I will do the next time she comes to Southern Cal to visit her friend Chennin Blanc), I did spend a wonderful afternoon with her in Vegas at AVN a few years ago.  She's cute as hell, has a great body, incredible attitude and mad oral skills!  I can't imagine she wouldn't be a good choice and from her review history, may even be able to find the third for you, something I'd recommend for the reasons noted above!   You may also want to watch the boards for the next time Chennin comes out there (which she does fairly regularly), I am dangerously close to positive that the two of them together would be awesome.  Came close, since I hooked up with Chennin the day before I did with Queeny at AVN and had a blast with her as well.  Good luck!