The 2015 calendar was a good calendar but this is what I would have done if I was in charge for F1.
Pre Season Tests:
19th - 22nd March
Pre Season Test 1 - Jerez
2nd April - 5th April
Pre Season Test 2 - Barcelona
9th April - 12th April
Pre Season Test 3 - Barcelona
2015 F1 Calendar - My suggested Calendar:
26th April
Australian Grand Prix
10th May
Japanese Grand Prix
17th May
Chinese Grand Prix
31st May
Malaysian Grand Prix
7th June
Singapore Grand Prix
21st June
Spanish Grand Prix
28th June
Monaco Grand Prix
12th July
British Grand Prix
19th July
Belgian Grand Prix
2nd August
Austrian Grand Prix
9th August
Hungarian Grand Prix
6th September
Italian Grand Prix
20th September
Russian Grand Prix
4th October
Canadian Grand Prix
18th October
United States Grand Prix
25th October
Mexican Grand Prix
8th November
Brazilian Grand Prix
22nd November
Bahrain Grand Prix
29th November
Abu Dhabi Grand Prix
Rule Changes:
Two week winter shutdown implemented.
Car launches done one car per day instead of multiple per day.