Well, I *don't* have a Griffon (yet).
I used a proxied Chimera a couple of times. The Beast always gets Bloodroar. The rider usually gets something like FP, enchanted shield/charmed shield, Dragonhelm, 4++ and some magic weapon - Biting Blade, Sword of Swift Slaying, Sword of Might. The gravest danger are bolters and cannon. Don't let some Reavers or Bowmen take away your charmed shield save and make use of LoS blocking terrain. To further increase its survivability - which against Dwarfs or bolter-heavy Elves isn't good - I like Pha's, Iceshard Blizzard, ample counter-battery fire and target saturation (two Captasi, STank, DGK, buff wagons...). Offensively, I use it to declare a charge on something preferably outside the General/BSB AoE's, preferably close to the Board Edge. Again, Iceshard on the target helps. I've found this to be quite useful, making chariots run off the table that I couldn't realistically reach. Not so good against Vampires or TK but at least the former have less shooting, and against the latter I throw him into his archers.
5 archers stubborn is not a tactic I'm afraid, it's a loophole. Charged frontally they will usually all be killed, so you need to present a flank - and it's utterly unrealistic that a unit would be of higher spirit (better off) if flank charged.
My fav play style includes mobility with some buffs, static or magical, plus the age-old hammer and anvil style. I often have a bus of Spears with a detachment, some knights of any description, a buff wagon and try to outmaneouver the opposition.