Originally Posted by
IAHtraveler
The other (cheating) trick is to use milecalc.com. You can put in your routing (only up to 4 segments, though) and it'll give you the total miles. On the second page, you can put in specifics (cost, airline program & % bonus, booking class bonus, promo miles, credit card miles, etc) and it will give you the exact cost/mile for both the 1-way our round trip option.
For a 10 second search, I found PVD-ORD-SEA for 2570 miles instead of your 2560 and it shows 8.17 cpm without any bonus mileage selected.