I do most of my driving standing up - looking over the windscreen - viz through it is pretty crap anyway.
If it's sunny, I wear my Oakley Eye Jackets - which are great - although care needs to be taken not get a really stupid tan-line
If it isn't sunny (or going dark), I've got a pair of OK looking safety goggles - £3.99 from Screwfix I think - which do the job.
If it is hosing it down, I'll wear the Gecko.
And as for hats - we have had no 'hat overboard' incidents since we invested in some of those hat saver things that clip onto your jacket - so if your hat blows off, it just ends up hanging behind you (and it means that you don't have to have your hat done up so tight that your eyes water, which brings us back to where we started...)