The difference between the "family members" clause and the "guests" is the number of folks you can bring in. If you bring in your family, you can bring spouse and a kid or two or five, provided all the kids are yours and they're all under 18. The "two guests" is just that: two people, doesn't matter the relationship to you. The whole "adequate space" clause is just so you understand, if they're jam packed, they HAVE to let you in because you bought the membership, but they don't have to let in spouse, kids or guests. And if they're over fire marshal occupancy limits, they won't let anyone in. I've never seen the US club turn anyone away due to occupancy but I have seen it with AC MLL in YVR when the transpac's are loading up, and also UA RCC at ORD.

On the reciprocal benefits with RCC/PC I believe you only get 2 guests regardless of relationship. The *A Gold lounge benefit on International itineraries works the same way: max number of guests, period, regardless of relationship.

As neotope points out, if you travel separately, the benefit of having two cards is neither one needs the other for guest access. You can each go to the club on your own. I suppose theoretically you could go to the same lounge and each bring two guests if you wanted.

PS you may want to get a 6-month membership which isn't the most cost-effective but you'd be looking at a renewal just a few weeks before the annual Grand Slam promo (assuming they have one this year). Go a few weeks without a membership and renew during GS for an easy hit. I'd rather pay a little higher half-year fee and have my renewal happen during GS and get the hit, than pay for the year now and renew 5 months early.