[rheavn]

"What kind of typical life cycle are you all seeing in the following list of items?"

My coach is 20 years old.  I have replaced air springs, brake chambers, radiator hoses and the engine belt.  None were replaced due to poor condition or failure, but replaced as preventative maintenance.  I have repaired a heater hose that failed due to chafing.  

I have never heard of any one replacing window seals or slide seals due to age & mine are original.  

I do inspect hosing annually as part of my preventative maintenance procedure.