Cap & rotor- you want brass contacts/terminals. You *Don't* need to $pend $eriou$ Buk$ for some big aftermarket performance name, just spend an extra buck or few for brass contacts. NAPA has such a cap & rotor, reasonably priced.
Plugs- in general, platinum plugs offer longer life, but not better performance- that usually comes from plain copper core plugs. OEM-type Champions, NGK V-Powers, or maybe Autolite 3923 if pinging is a problem, should let your 3.9 run to its full potential- and all those are pretty cheap too.
Just be prepared to change them every 35,000 miles or so.
Wires- more nonsense goes on about plug wires than almost anything else. A plug wire is a conductor, it does *Not* make horsepower! Don't get pulled into the "resistance wars" some sellers advertise either- an electrical phenomenon called "skin effect" renders that useless as an argument. Best tutorial on plug wires I've ever seen is at the Magnecor site- just google "magnecor spark plug wires", find their website, educate yourself- and you don't have to buy their wires either! However- if you *do* decide to buy expen$ive wire$- you can't do better than Magnecors. Otherwise, any house brand spiral wound silicone insulated wires from any parts house like NAPA, O'Reillys, etc will serve you well for a few years at least.
And if anyone tries to sell you something called Nology wires- Run like hell!