Dave,
To obtain consistently listenable recordings with a tight bottom end that doesn't overdrive small speakers, get into the habit of shelving below 50-60Hz. The higher you start shelving the tighter it will sound but you'll obviously get less "motional" bass coming through on monitors that can reproduce it. If you want both, try shelving with a gentler roll off but a higher "knee" frequency. For instance, yuo could shelve at around 80Hz but with a slope such that you only end up with say, 15dB cut at 20Hz.
There are a few things you should keep in mind with regard to bottom end issues. In most average listening rooms you'll get considerable amplification of frequencies below 50Hz by standing waves and half space/quarter space issues (ie. speakers near walls or corners). To give an example, my monitors have a free field cut-off of around 45Hz and I built a complimentary EQ circuit to extend this down to around 28Hz. I've yet to have a room where I found having the extra bottom end helped. In my current room I can easily hear sub bass and it is pretty much at the level it should be. The other thing to keep in mind is that, as far as I'm concerned, sub bass sounds best when it is subtle rather than overbaring. Remember that the harmonics giving it spacial definition are at a much higher part of the spectrum (between 100Hz-1kHz) and if ther relativities of the two aren't right you'll loose that sense of "space" and it will just start sounding wooly.
I've found a good indication on whether the sub bass is about right is how often it fools you. What I mean by that is that often I've listened to a new piece with sub bass in it at moderate levels and then think "did a truck got past the house". Invariably I end up pausing the recording to check if that was ouside noise or something on the recording.
I guess that is what I mean by sub bass having the right subtlety. If it makes you think the ground is shaking (rather than you) then it's probably about right. Then again, I guess it's a matter of taste, going by the average "fitted out" car with thumping bass. Personally, I've never found that level of bass attractive.
Cheers,
Paavo.