Because men are often in the position of "suggesting" the whole idea of swinging, and their wives may be reluctant to pursue it, they expect that the women will have a hard time enjoying it. But the fact is, most women find the lifestyle to be a sort of "freeing" kind of thing. Suddenly they are getting attention from lots of different men, who do not seem to be put off by female middle-age droop. The lifestyle by its nature is one big opportunity to lose some inhibitions and learn to enjoy sex for sex's sake, without the baggage of being called a slut or the guilt of having sex with someone she doesn't intend to marry or raise children with. Suddenly they are having a sexual experience that's totally different from the one they've had for the past however-many years... and they are really enjoying the renewed feeling all this gives them. .. and most women welcome the opportunity to have such an experience.
Also, whether it's fair or not, men do a lot of the "pursuing" in the lifestyle, so the gals often get more attention than the guys at a club event. The guy may find himself feeling a little left out, and may think his wife is enjoying herself too much... and may be wondering, what kind of Pandora's box did I open here by even suggesting this?? In order for it to enhance rather than hurt your marriage, you both have to be getting equal pleasure from it. Any other circumstance means resentment could build and damage your relationship.
A word to the men who are intent on "convincing" their wives to try this - guys, be careful what you wish for, you just might get it!! Meaning, you might find that your wife REALLY enjoys herself - and you'd better be prepared for the possibility that she'll get more attention from the opposite sex than you will.
And ladies, your word of caution is simply this: Enjoy the bit of sexual freedom the lifestyle affords you, but remember who you're going home with, and make sure you are not the only one having a good time.
I don't think it's fair to allow your spouse the opportunity to experience other partners if you are going to put limits on how much s/he is allowed to enjoy it. You have to trust each other to know the difference between sex and love, and understand that just because a person appears to be enjoying the hell out of themselves doesn't mean they are thinking they've found your replacement.