Few days ago, I was contemplating a golf vacation and a mini-MR to Tampa in the fall to take advanatage of double miles promo. I found this on ITA:
SFO – DEN – MCI – ORD – CLT(US) – TPA
TPA – MIA (CO) – MCO – DEN – SFO
for $324.20

Another one:

SFO – DEN – DFW – ORD – TPA
TPA – DEN – ONT – LAX – SFO
for $310.90
For this itn, if you have Elite bonus, plus double miles. Cost per mile is about 2c+

I did not book it due to some uncertain about the dates. Don't know if the above are still avail.