My group is just beginning to tinker with the idea of kaiju for our local convention event
this year - though our adventure arc is more about the creation of kaiju than fighting them - villains smuggling 'special' dinosaur eggs from the Living Land, doing things
to them, all the while messing with Core Earth, each other, and their own people.
We're still in the first phase of planning (we haven't even decided if the kaiju is any more than a post-credits cookie for our adventure), but if it comes to a fight, we'll be working hard to make it epic.
Honestly, that's the biggest problem I see with things like kaiju and mecha - to keep it interesting for all the characters, not just the pilots and shooters. The last thing I want to be part of (either as GM or player) is a game of 'mech pilots and their amazing sidekicks,' where all the important action is giant things hitting other giant things, while everyone else just dodges debris. For something like Torg, as far as I'm concerned, kaiju are best kept as SFX, or maybe the occasional looming threat.
For myself, I've never been all that enthused with mecha - they're amusing, but I'm much more interested/excited by the application of more mundane technologies and techniques - missiles, tanks, planes, and sheer ingenuity - than by stuff that's just big.