Help with best practices for assemblies

Im looking for some help with best practices... I am starting to work with a customer who need some pipework drawn up.  These will mainly be building assemblies.  Without the routing add in, what is the best way to go about bringing in different lengths of pipe?  Is this something where I need a library of pipe of all sizes?  I'm fairly new to this, and would love to hear the options for completing this efficiently.

SolidworksGeneral