Personally I'd make the Spanish alternate between Valencia & Barcelona and free up the European GP to go to tracks we'd like to see back in F1 like San Marino. Spain should not be allowed to have 2 tracks in F1, dull ones at that! No country should. It could alternate between Venues around F1 and give us something different to look forward to each season and offer the countries a cheaper way back into F1 or even a new country a way onto the calender.
I'd put France & San Marino in as European GP races, I'd also stick Hungary in that bracket, frees up another space for a decent track. Also if a track like Turkey can't afford a long term deal due to a lack of people then it would not completely be lost to F1.