Thanks for these reviews - I have also stayed in both of these FS, so always interesting to read others' experiences.
Re breakfast buffet at FS Bosphorus, we stayed there in May 2009 and had the same issue with birds and wasps. Like the previous poster, that also put me off the buffet, but the a la carte breakfasts were excellent and that vast marble terrace by the Bosphorus is simply stunning.
We went back to Istanbul in June of this year for a weekend and tried the Ciragan Palace, as we couldn't get into FS Bosphorus. I found the service at the Ciragan even better than at FS Bosphorus and, for me, - the CP had the very slightest edge (despite our suite bathroom having a shower over the bath - which is something I really don't like).