Down below?
 

Ok this is another either or question- my Queensland friend says there should be nothing below the benches to stop pests from gathering etc, yet Geoff from local orchid club has ferns and babies tears growing below the benches.

I've also read and seen many other GHs with people growing stuff below the benches such as ferns and bromeliads that help boost the humidity.

So what is better- nothing below the benches or?

I should add the baby's tears apparently keeps growing into the middle path and handfuls of it have to be ripped out and tossed out regularly!

I've heard both Damian so I'm no help. But given the choice I would do whatever I could to increase humidity. You're going to check your 'chids' for pests anyways so you should be able to keep everything at bay, even in the non-chids.