If I don't do it as a bass-line ill sometimes throw them in over kicks to add some more bounce to the track. Other times ill just isolate the lows on my sample and play a bass filtered version instead of the sub bass.
if i knew how to make proper sub bass id include it in all of my tracks. Unfortunately for me its something i have trouble getting right and often times will not include it for the sake of just getting on with finishing the track and moving onto something else.