Have a look at Concept Draw.
May be a better fit than Visio for your pocket book. Have used the demo for network layout (floor plan, rack), flow charting (old school), and org charts.
Otherwise you would have to look more towards a good CAD program, which do tend to have steeper learning curve.
My favourites other than AutoCAD (too pricey for hobby work) These are over the top for most of what you wish. This is what you pay other people to know.
http://www.datacad.com (DataCAD LT)
stripped down 'home version'