Bike Direction on Roof Just wondering if anyone has any thoughts/suggestions on which direction bikes should sit on the roof 

I've Thule bike carriers which can be left or right opening. 

So do I place both bikes facing forwards, or do I have the bikes one front facing, one rear facing? 

If the answer is simply try it and see, so be it, just wondered if anyone had experience of whether one option is easier for mounting the bikes, or provides less wind noise etc.etc.etc. 

cheers
Mainly it doesn't matter.  Usually two bikes are front-first (because it "just seems right"), but once you go beyond two bikes the directions alternate.  True, if you don't have the bike properly fastened then, on a fork-mount carrier, it can blow loose a hair easier in the reverse orientation, but it can also come loose going around a curve or going over a bump, so you need to be sure it's well-fastened in all cases.

Note that you may find, based on whether you're right-handed or left handed (or maybe you have a bad shoulder or such), that it's easier to lift the bike onto the roof one way vs the other.  In that case it makes sense to have the bikes front-facing on one side and rear-facing on the other.  OTOH, the shape of the vehicle, position of the doors, etc, may factor into your orientation decision.