Miles used for coach flights usually are worth one to two cents per mile. Last minute flights are more costly and sometimes can be flown for standard miles. Still I value miles for domestic flights at 1.6 cents and Starwood because of the bonus at two cents.
The real value of miles is for international business if you can get a seat. I flew to London recently however on a advance purchase business class seat for about $1,850. It would have cost me 100,000 miles plus I'd have lost 8,250 base miles for the paid ticket, my 50% bonus for class of service and my double gold miles. All told, the miles would have netted me about a penny each so I paid for the flight.
On the other hand, I have used Starwood points in London, Dublin, Chicago and Los Angeles recently at values of three to six cents each. Remember when calculating value to add tax to the quoted per day rate.
Now my best use ever for flight miles was to SYD in business class. That was several years ago and I got two $8,000 ticket for 180,000 miles total. Actually, though through various discounts I could have bought the two tickets for about $9,000 total. That is still five cents per mile.
Recently I tried to use miles to China. I gave up as no simple routings were available and Air Canada had a $3,100 ticket from LAX. Adjusted for miles used to get to LAX and miles lost flying on an award ticket, this would have cost me net 100,000 or three cents per mile. However, the times were miserable and would have added hassle and cost (a minimum of an extra day's hotel and meals), so I bought the ticket.
I plan on using my miles mostly on hotels. Will continue to try on last minute and costly flights. Starwood has the best availability of airlines and good (maybe not the greatest, but more than good enough) hotel choices so it gets all my charges excert where either AMEX is not taken or my free Citibank card gives a 5% cash back rebate.