Since we're throwing out our ideal PPV schedules, I'll throw this one out there...it's a little different.
January: Royal Rumble (co-branded PPV)
February: Saturday Night's Main Event + Roadblock (2-hour Network Specials)
March: Wrestlemania (co-branded PPV) + NXT Takeover
April: Spring Stampede (Smackdown PPV)
May: Backlash (Raw PPV)
June: King of the Ring (2-day Network Special) + NXT Takeover
July: Great American Bash (Smackdown PPV) + Saturday Night's Main Event (Raw 2-hour Network Special)
August: Summerslam (co-branded PPV)
September: Fall Brawl (Raw PPV) + Clash of the Champions (Smackdown 2-hour Network Special) + NXT Takeover
October: Halloween Havoc (Smackdown PPV)
November: Survivor Series (co-branded PPV)
December: Battleground (Raw) + NXT Takeover
I actually removed regular PPVs in favor of 2-hour Network Specials. SNME and Roadblock to bridge Rumble and Mania, KOTR as a UK-tourney style event and another SNME and Clash of the Champions to counter an opposing brand-specific month. I figure it adds purpose to the Network and can advance and build storylines. I limited NXT to 4 quarterly Takeovers, with 'Mania weekend being the only one bundled with a major PPV. I may be in the minority, but I preferred the original setup for Takeovers, even having them on Wednesday nights.
Edit: Forgot to mention that I removed Money in the Bank as its own show in favor of moving the match back to Mania.