ydnpa, a slightly belated thanks for the tip -- we ended up staying at The Cliff, which was a little over my planned budget at Christmastime, but goes for under $100/night in the off season. It's a great little place with infinity-edge pool looking over the Ao Nang cliffs, Balinese-style garden in your bathroom and very friendly service, just the kind of place I was looking for. ^ Location is pretty good too, central to the action (quite a few restaurants etc within 5 min walk, perhaps 15 min stroll down to the beach) but still very quiet. Downsides would be that the bungalows and the entire resort are a llittle on the cramped side and, despite what some agents say, they do allow families with kids (although hyperactive toddlers and colicky babies were mercifully absent).

Krabi in general was surprisingly full of people, almost entirely German and Scandinavian, with Rai Leh in particular packed to the gills. Quite frankly I feel sorry for the people who forked out US$500+/night for Rayavadee, the grounds looked nice enough but its notionally "private beach" was absolutely inundated with hordes of sun worshippers, coconut sellers and kayakers like yours truly daytripping from Ao Nang. Beautiful place though!