How do I decorate my home that has a very open layout?

You’ll have to keep everything clean!

It’s nice to use different colors to separate the areas but have them all co-ordinate with each other for a visually pleasing effect. I have a “great room” in Florida and have off-white walls with and neutral furniture with beige, blue and yellow accesories. It flows together very nicely.

I love to use furniture groupings to create the effect of solid structures (walls). If you have a lot of space (lucky you), then you can bring in tables of various sizes to serve where wallw would othewise close out a room. And @janbb‘s advice is spot on—mix up the colors and patterns a bit to create different pockets of interest, but keep some elements common throughout so that you have a very harmonious feel.

This site has some great Photo ideas