In reply to Robster29: Depends on the grades you are looking for. In the UK for grades in the 6's I would say Portland. I understand however that the Peak and Yorkshire are better for the higher grades. Abroad I would have to agree that Kalymnos takes some beating for convenience but I prefer France overall because of it's general ambience and the quantity of climbs although they are of course much more spread out.
In reply to Robster29: IF you're a hard climber then the Tarragona area of Spain is brilliant. Got huge, classic areas such as Siurana and Margalef. I've been and it was the best weeks sport climbing I've ever had!