So I know your wife is really excited about this guy (and I THINK nothing has happened yet between them besides flirting?) but I would be apprehensive about starting out by being involved with a person who doesn't have experience in open relationships, OR is a really good friend.
There are LOTS of poly people here in Seattle, and although it's no guarantee, dating somebody who really understands "can be" safer in some ways than somebody who might try to act like a monogamous boyfriend if he falls for her and the lines are blurry. The first person I really dated when I was previously married had been poly for 20+ years, so I got to learn a lot from him, his knowledge of healthy boundaries was good and he understood that I wasn't unhappy with my marriage and hoping I'd run away with him. On top of that, he introduced my husband to an awesome chick to date.
So maybe she and you want to check out (if you haven't already) okcupid.com and search for poly/amory in the area. I am sure that you would find both friends at the least. I have been to the CSPC poly potluck once, but not to the other couple of local meeting things - if whatever you find isn't to your liking, there are lots of other options to network. I think how much fun you have may depend on how outgoing you are feeling at the time.
Only thing that I'd say is when you say she'd like the chance to flirt and "act on anything that might come up" is...are you OK with that? Have you talked through safe sex agreements, do you think that if she came home and told you she'd done X act, you'd be unhappy? or that you'd punish her in some way for doing more than you thought she'd do? Lets say the acting on something was checking into a motel after hockey and having sex - if you aren't clear about what you are or aren't comfortable with you could always be in for a rude surprise. I stress this partially because she has stated that your sex life is not for better terms - as big of a factor in your relationship for her as you thought it was, so it's always possible if she has sex with somebody else it could be more stressful now that you know this.
My husband and I talk about things ahead of time, if we are dating somebody and wanted to move from kissing to making out, or from making out to getting naked, we'd let the other person know ahead of time, so there weren't big surprises...it'd sure suck to have had a crappy day at work and come home to find out that your partner jumped a few moves ahead of where you were comfortable with. That leads to unnecessary potential for arguments and can make things that aren't really that big a deal into being a big deal.
Happiness will never come to those who fail to appreciate what they already have.