In reply to ScubaFairy:
I visited Siurana easily, my top leading grade is F6a and seconding if I'm lucky F6c. I found it tough in Siurana itself though if you were pushing 7a's comfortably then it would be much more worthwhile (it was really good for friends who were redpointing 7a). It's definitely worth a visit, amazing place.
We also made a couple of day trips to Margalef. Extremely worthwhile for 6a's and up. The stuff in the valley is repetitive and not worth bothering with. Go up the small windy roads for the best stuff. The crags on the very tops of the hills were amazing. I bagged my first outdoors 6a lead there - 30m of amazing moves. Again, worth a visit for sure. For mid-grade, Margalef is a bit better than Siurana, though there is less there on the whole.
(For Margalef you can buy a guide in the village, for €10)
Hope this helps!