It depends on your itineraries - works well for me as all the clubs at my home airport, SEA, are accessible (although the Crown Room is a really long hike for other than DL or AA flights!). Came in very handy at BOS last week. I was transferring from AS to CapeAir; CapeAir wasn't going to be staffed to hand out boarding passes until almost 2 hours after my redeye pulled in, so I was able to "decompress" nicely at the CO club nearby (before security) while waiting.
One of its strongest features is that you don't need to be ticketed on the club's carrier to gain entry - just show the card.