Amen, sister! I have spent most of my life trying to take care of everyone, be the perfect hostess, plan great parties, etc and I spend a ton of time being tense and terse before big events - making lists, trying to attend to every detail. This organization before the fact helps me be able to relax and enjoy the event itself, but I am occasionally reminded that some of our best times have been spur-of-the-moment parties, dinners and get-togethers wherein I throw toilet paper down the stairs, apologize for the dog hair on the babies and just enjoy the companionship and fun. Perhaps the trick is to lower everyone's expectations in the first place! :) 

For me, it's about allowing myself to enjoy and not feel like I have to be in charge of everyone else. If all else fails, open another bottle of wine!