We have a fake tree. It's rather narrow, because there's not much space for a tree in our house. We used to have a wider fake tree, and would have to rearrange all the furniture to make room for it. This one fits a lot better, but it looks a little sad (like it's anorexic) until we load it up with ornaments...
We have a ton of ornaments. There is no rhyme or reason or "scheme" with them. My mother started me out years ago by giving me a bunch of old ornaments - she wanted to go all decorator with her own tree so she packed up the old ones and distributed them to us kids. I even have a few ornaments that are from my dad's childhood tree. I have to treat them carefully as they are quite fragile.
Every year, we add one new ornament per person. It's a family tradition to go ornament shopping together. So we have ornaments that remind us of past years - whatever we were interested in that year. I also have a lot of homemade ornaments the kids made when they were younger. And ornaments given to us as gifts - one of my favorite presents to receive!
Our tree this year is topped by DD's boyfriend's hat. He is never without his hat. But it recently developed a hole, and he had it replaced, so he gave us the hat with a hole, and we put it on our tree. Because we are silly like that.
Other decorations: when my kids were young, I went through a crafty phase, and would make santa clauses. So I have a bunch of santa clauses we set out each year all around the house. My favorite is a "jogger" Santa, who has a red hoodie and red running tights.
We also have a set of cheesy, inexpensive apple ornaments. You probably know what I'm talking about. These were given to me by my ex-MIL when the kids were very young. The idea was to hang them on the bottom of the tree, where little fingers might want to play. They are cheap and unbreakable and safe for young kids. Every year the kids still want to put these on the tree, near the bottom. This year, we did not - but we did stick them in a pretty bowl. They are quite tacky looking but it's about the sentimental memories more than anything else.