Since I threw the questions out there I suppose I'll take a shot at answering.

Not going to take any races away since there aren't that many to begin with.

Add: Phoenix, Richmond, Kentucky, Watkins Glen, Circuit of the Americas, Boston street course.

Schedule:
St. Petersburg - Season opener, early March
Barber MP - mid-March
Phoenix - late March
Long Beach - early April
NOLA - mid-April
Texas - late April
Indy GP - early May
Indy - Memorial Day Weekend
Milwaukee - early June
Belle Isle - mid-June
Richmond - late June
Boston - early July (4th of July weekend if possible)
Watkins Glen - mid-July
Iowa - late July
Toronto - early August
Pocono - mid-August
Mid-Ohio - late August
Kentucky - Labor Day Weekend
Sonoma - mid-September
Circuit of the Americas - late September
Auto Club California - early October Season Championship

I attempted to follow a guideline of 3 races per month, 21 races total. I also attempted to avoid conflicts with NASCAR races at certain tracks, preferrably at least 2 weeks between NASCAR and IndyCar events at the same venue. 9 ovals of various different sizes and configurations, 7 permanent road courses, and 5 temporary street courses. Other races and tracks could obviously be added with at least 1 open weekend in each month. I left off places like Chicago, Atlanta, Charlotte, Las Vegas, Michigan, Elkhart Lake, etc. that could be good choices for events. Many could easily be swapped for events in the same area on the current schedule.