I would say both. When recording, say, blues, rock, hard rock, or really any type of rhythmic music then I would still lay out the instruments in a stereo configuration that mimic stage positions; lead vocal, drums and bass in the middle, instruments that occupy similar frequency ranges go in opposite sites. From there I'd play around to see if some other interesting aspect comes up.
There's a reason why most band configurations look similar, across a wide range of genres -- from symphonic orchestras to heavy metal bands to R&B and hip hop. A lot of it has to do with making the instruments work together nicely to produce a coherent sound. The ability to see what's going on (the conductor or the band leader) also plays in. So even if you're making music just with synthesizers and samples, certain sonic properties like the fact that we can't detect the direction of low frequency sounds will probably make you end up placing the bass and drums at the center of the mix. If you have two synth sounds that occupy the same frequency range, placing them in each side might prevent your mix from sounding muddled too--just like the example with real instruments above.
I think the key thing is to try a range of options. If you do something very out of the ordinary, even listeners who are not audio production savvy will notice and that might divert their attention in a direction you don't want. But in other songs panning the lead vocal hard right might just be the thing you were looking for.
If you're mixing for a wider audience, don't forget to listen to your mix in mono too! Some people might be listening on a mono-setup or have their speakers really close to each other. Your mix should still sound good in such situations, and any gimmicks relying on clever panning will obviously be lost on those listeners.