We also did Hebrides in May (2008) and had the wind against us going North! We rode the west coast of Harris to Tarbert in a full on rain storm and howling northerly wind. Particularly memorable bit was having to pedal our heavily laden bikes downhill into Tarbert against the wind. Never was a pint in the Harris Hotel more richly savoured...
Would agree with what Rik said - absolutely awesome trip. Scenery and wildlife were amazing, and it was also one of our best holidays ever. As well as Harris, I really liked the NW coast of North Uist - really open and wild and not so much traffic as on the main Harris coast road. The east cost of Harris (The Golden Road) is also stunning.
South Uist can appear a little featureless in parts, but some great mountains on the East side (almost completely deserted), and cracking beaches on the other side. We rode a good portion of the trip on the beach or tracks across the machair.
We travelled S to N but then got the bus back down the islands with our bikes and spent the last couple of days chilling on Barra and Vatersay before getting the ferry back.
I really fancy doing a ferry from Oban, a circuit of Mull, over to Morvern / Ardnamurchan on the foot ferry from Tobermory and then on up to Skye sometime - anyone done that route?