I have an '05 Rendezvous. I just finished waxing it with Meguiars Nxt Generation tech wax. This thing has big lexan lenses that cover all the headlights and signals and the entire back is one big tail light lens.
Will waxing these lenses do any harm to the plastic?

No.

Wax away.

I love the way my headlights look after a nice coat of wax (hey, that sounds a little racy! LOL) You can even wax your glass, if you so desire.

No only does it look nice, wax helps protect your paint, hard plastic and glass from road gunk, acid rain and other such nasties.

Just make sure you use a true wax and not a cleaner wax. (I.E. a wax that also contains an abrasive in it and may scratch your plastic). Also keep your wax away for the rubber trim or textured plastics because the wax residue can get trapped in these materials and appear as "stains".