[SoundWrangler]

Have to agree with Doc re: use of stereo enhancers; for me they can generally be used more agressively on a sub-mix rather than the whole track. For music in particular (& as has been mentioned in previous threads on this subject) any more than a very small amount of S1, etc. applied to an entire stereo mix tends to be negative for elements in the center that you'd prefer to be really solid (like a kick drum, or a punchy bass gtr). For me, it generally works better to put this type of effect on a stereo Aux, to select which tracks will benefit from being routed through this kind of treatment.
Stereo "widening" is never a positive thing for mono compatibility, though. (Not a concern for my work, but for broadcast video post guys espec. it's something to keep in mind.)

Another (widely-known) tip regarding delays in music mixes: take the trouble to make your delay times correspond to some note value at the current tempo (i.e., 1/16, 1/8, 1/8 triplets, 1/4 triplets, etc.) - this can reduce some of the "clutter" Ben mentions above, from random, non tempo-related timing factors clattering around inside your mix. (Some people also apply the same idea to longer reverb pre-delays.)