Funny I had an Uncle that flew F-14's in the 80's. Did you know that for every hour that bird flew it took 80 maintenance hours!!! Great aircraft but a bit labor intensive to say the least which is why they were fazed out early.
In comparison the F-18E takes 12-16 maintenance hours per flight hour.
And as far as F-15 airframes I believe some of the later ones have quite a bit of life left on them as they are to remain in service at least another 15+ years.
And interestingly enough there was a concept proposed to the navy to buy Su-27\33 airframes and load them with American engines, avionics, weapons systems and radars! The cost was incredibly low compared to home built aircraft and a deal was even on the table with the Russians before the pentagon pulled it.
I am just saying that defense budgets are out of control much like Washington's budgets.
Time to make the market competitive again.
Oh you cannot build it for what we agreed on? Fine cancel the contract we will be looking elsewhere.