What's a good tool create a floorplan with?
I'm not sure if Software Recommendations are on topic at DIY.SE, on a lot of SE sites they aren't, but it's up to the individual site's 'community'. 

That being said, Sweet Home 3D is easy enough and free enough to create a floor plan. Here's where I include a screenshot for bonus points:



Also, (formerly Google) SketchUp would probably accomplish a decent floorplan as well.