I found this virtual room designer while I was scouring Pinterest awhile back and I just tried it today!!!
It's called Icovia Space Planner.
Here is MY living room/dining room with MY dimensions!
Everything is quick and easy to make into your sizes from the walls, the sofa, and even the dogs! Did you notice the Christmas tree? It has tons of little things that personalize your space.
It loaded up really quick and easy, it was easy to use, and you can save your layouts! How cool is that!
My room doesn't currently look anything like this and I was having a really hard time visualizing it all since I can't just scoot around my 90 gallon fish tank or the TV armoire at whim. Now that I can see exactly how it will all go together and how it will fit .
Anyhow, give it a try. It's free.