It's funny but I was in someone's home recently and everything was perfectly done--except for one thing: the coffee table felt way too close to the couch, for me anyway. I think it's a personal thing that depends on how tall you are, whether you're trying to walk past someone else who is also sitting there, etc. Our coffee table is 18" from the loveseat and about 21" from the couch, but I think it gets moved around a lot so people can put their feet up. (It's temporary furniture.)
Do a mock up in your room or take a trip to the local furniture store, and bring your tape measure.
Q