Lounges for different airlines in different airports are really hit or miss. If you think you will need an agent's help during your delay, just get a pass for the airline that you're traveling on.

If you're on the outbound part of your journey, consider that NW offers a 60-day pass for $125; you can bring in 2 guests, and you can hit the lounge on your return too.

Just noticed you're in SEA - you can sign up for the AS Visa card and keep the free Board Room passes in your wallet.