Usually the trial version also includes information in the files that prevent them being opened in any other version. Not sure if this is true of smartdraw, but it is a technique to prevent a large organization from getting a lot of people using the trial version and one paid-for version to finish the work.
I think I tried smartdraw a long time ago and it wasn't so good, but it was really cheap student version. I guess they don't do that anymore.
I have used Dia, a free software for complex diagrams and generally liked it a lot, but it may not do everything you want.
Have you tried screen-shots and pasting the images together?
(To add - for me applications are like pets and not every app is the right one for every person; they need to be the right size, the right amount of effort, and produce a sufficient sense of satisfaction. I had access to a $10k a year licensed CAD application and needed a purely 2D diagramming tool that would run everywhere I needed to be - thanks Portable Apps. I could have used some EE schematic capture app, which I didn't have and they typically require a large up-front effort to even start. Dia was the hamster I needed, not the tamed bear I did not. Dia would not be as good for home plans and not as easy for duplicating an org chart, but - it's free - I'd pay for a month of smartdraw if I needed it, but paying for a year when I only need it for a week? )