Sorry Steve I know we should wait
bump is spot on there...
If I'm writing something, I find there'll usually be certain chord tones that are essential and some that can be dropped because they just arent needed to get the point accross.
The 5th is usually the first to go, because as bump said it isnt usually needed to reinforce the sound of the chord.
Each note on your bass is made up of natural harminics. The perfect 5th of any note is the nearest note the root itself in terms of the harmonics it contains... which is why it has little effect on the tonality of a chord.
You can hear this clearly If you play a Maj7 with the 5th voiced, then replace the 5th with the 3rd. You'll notice that the 5th sounds more 'vanilla' flavoured... "it goes with anything" ...if that makes any sense?!
I tend to not play 5ths in chords at all anymore as they do just increase the mud factor... unless that's the intention of course.
Depending on context, another thing you could do is not voice the tones that give the chord it's tonality, then you can change the tonality using melody or bassline
