The problem with hard coding the space is there are times it is not wanted/needed. I am stealing the following from xpsace documentation.

Input with "\newcommand{\gb}{Great Britain\xspace}":

  \gb is a very nice place to live.\\
  \gb, a small island off the coast of France.\\
  \gb\footnote{The small island off the coast of France.} 
  is a very nice place to live.

Results in the output

  Great Britain is a very nice place to live.
  Great Britain, a small island o the coast of France.
  Great Britain[^1] is a very nice place to live.