I simplify by skyping instead of visiting, and giving cash or donations to charities instead of gifts.

For Thanksgiving my mom wanted us to come over (4 hr drive) even though we are coming for Christmas. I told her no, but we would skype in. I got my sister & her boyfriend to skype in too, from Ohio (12 hr drive). And my brother and his girlfriend were at mom & dad's (5 min drive). During the "get-together" I took a screenshot of all 9 of us and titled it "Norman 'Skype' Rockwell".

It was a lot less crowded.

For gifts, I've taken up asking for donations to my favorite charities, and giving donations to charities for the adults. Except some adults get gift certificates if for example they are starving students! For the nieces & nephews, it's either cash or a present, depending on how inspired I am. This year, they are getting cash, the money in a card addressed to the kid...sort of!
Actual names: Samantha, Joseph, Draven, Morgan, and Tia
Names on the cards: Samuel, Josephina, Dravenia, Morganator, Uncle Tio

My husband, daughter, and I exchange more meaningful gifts than cash. Although this year I did ask for a donation to a special charity (the new trail, I'm on the steering committee).

For me it's not so much about simplifying the holidays, as it is about emphasizing what is important and not wasting our time and resources on what is less important. We love decorating, and our decorations are fairly simple. A tree, a nativity set, and advent calendar, stockings, a few knick-knacks. I don't put lights up on the house, they're pretty but it's a lot of work and wastes energy (my parents have solar powered lights this year!) I'll make cookies for friends and co-workers.