The valve job should include seals, seats, etc. as well. It should also involve some machine work like polishing the ports and a 3-angle grind on the valves. Your valves may not be bad, but parts DO eventually wear out.
If you are going to tear off the top end, you might as well get everything in it freshened up while you are in there. Otherwise, sometime down the road, you will have to go back in to replace stuff you could have gotten done the first time around.
And considering the present value of money, it will cost you more the second time around...
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car