Thanks again for the advice. Just thought I'd let you know how I got on.
Didn't actually manage to go down the Keys at all
- the weather was too unperdictable and I had fears of being stuck down there. Lost 2 whole flying days to mist and rain as sucessive fronts passed (very slowly) over Southern Florida.
Anyway, did get to go to Venice, Everglades City and across to the Miami area (Tamiami). All in all a great experience - can't wait to go back, but perhaps to somewhere with more interesting scenery - the Everglades are BIG and green and wet, but not much else.
Anyway, a few piccies
here if anyone's interested.