We added in the egg-crate mattress pads to the bunk beds. However we only have a 7yr, 4yr, and 3yr old sleeping on them.
My wife bought a "Memory Foam" topper for the master bed, and boy did it make a HUGE difference. I Think the one she bought was only 1" think but it was a huge improvement.
2009 RAM 1500, 5.7 HEMI + AirLift Air Springs
2013 Jayco White Hawk 28 DSBH
2007 Palomino Stampede 21RGS Hybrid (traded in 2013)