Hire someone to come professionally measure and draw the space. That way you will have them in CAD and PDFS format. You want to make sure the drawings are as accurate as possible and that you capture every inch of rentable space. This is a (very) small investment that pays for it self time and time again.
It's not a high end CAD program and probably won't cut the mustard for architects, permits, etc. But if you just want to measure up your rooms and then experiment with different layouts, furniture arrangements, etc, it's perfect and pretty easy and intuitive to use.
It's particularly useful for visualizing your designs and showing them to contractors and clients. I'm including a couple of pics below (starting with a completely gutted 10x10 space): one is the kitchen I designed using the app, and the other is the actual finished product.
At a cost of less than 10 bucks for the App, it's worth spending a few hundred on an iPad if it meets your needs!