Ahhh, got it!
When You need a software for professionals then it is sometimes necessary to buy a professional sofware which costs some money. A architecture CAD software for experts must be stable and fit all needs. Otherwise You are not so much productive. So You have to pay for the software but in long term You safe money.
Besides Draftsight I know two professional CAD tools You could use for architecture. I guess You must test both to get a feeling which one is better for You!
1. Briscad ( starting at 395$ ) http://www.bricsys.com/en_INTL/
Bricscad reads and writes the .dwg format and offers very high compatibility with AutoCAD®. The availability of a constant growing number of third party applications makes Bricscad the best solution.
2. CYCAS ( 298$ ) http://www.cycas.de/produkt.php?s=en&sys=lin&v=pro#top
CYCAS is a piece of architectural software for drafting and design in 2 + 3 dimensions.
In addition to typical CAD functions, CYCAS offers special elements and techniques for architectural design. Therefore, you can easily design and draft your ideas.
Would be great if You could give here a little feedback about both tools.