The good thing about the Takeoff Suite is that you can buy the whole thing or just the pieces and parts you need. Many contractors only need the functionality of Construction and CADNet so, unless you need Trench and GeoTech as well, you could save a little money by just buying those modules. And you could always add the other pieces later if necessary.
Construction includes most of the functionality you will need for building models and doing takeoffs: tools for elevating 2D to 3D, site and roadway surface modeling (including resurfacing), quantity calcs, exporting to machine control and more.
CADNet includes the digitizing and imaging tools such as raster to vector, importing PDFs and BIM files and more.
GeoTech is for importing borehole data for analyzing subsurface conditions and materials.
Trench is for calculations related to installing pipes, sewers, or utility lines.
One other thing to note is that Construction is mostly a blend of the functionality you’ll find in Carlson Survey & Civil. Since the pricing of Civil Suite is the same as Construction, you may find that purchasing Civil Suite and CADNet is a good alternative to Construction and CADNet.