Yeah man, against combined unit types preds and land raiders are the shiz but if you really want to piss off your opponant (troll face) then stick a cult of thousand sons in there with 2 more land raiders to get the RA on infantry so that you get a save against macro barage weapons. Yeah it boosts the unit to a hefty 875 points but its a nigh unmovable stain on the battlefield kicking out a lot of firepower every turn and you can always recoup your activation count on forlorn hope formations and a small formation of raptors etc.
Another cheesy thing you may want to try out, as it has worked for me when I have tried it, is having a Black Legion retinue with a Khorn cult and havocs transported in rhinos with a daemon pact and icon bearer and champion (again a hefty 780 points but hear me out).
Get it to within assault range of the enemy's best intermingled unit (generally an IG command HQ with demolishers in it when I have tried) with some summoned flesh hounds up front to take the hits (as long as your opponant is happy for you to use the additional daemon rules).
Now you are going to take some hits but dont worry too much as your daemons will soak most of them (try to use this as a last/first activation).
On the next turn, summon a greater daemon if you can and pile in. The flesh hounds and berzerkers will close down a lot of zones of control as you will have them up front, also the greater daemon can barge through infantry, but once this is done then (and here's the cheesy bit) throw your rhinos into close combat with his demolishers (or wraithguard in your case to stop them using their macro weapon) to make them use their close combat stat. You are going to lose your rhinos but once you are in assault range they are next to useless anyway and with any luck at all you will be causing waaay more deaths than the enemy.
Once this is done (if playing against Eldar) more than likely you will have a nightmare unit sitting on his wraithgate and he will have lost his supreme comander.
Now here is the important part: get ready to duck. Your opponant is now going to throw something at your head so be ready

p.s. only try this once. It is funny to use rhinos in this way but could be seen by some as cheesy in the extreme.