After 20 years, it is time to buy a new mattress.  I know it is a
matter of personal preference, but is there one type/brand of mattress
that is generally considered superior?  What makes for a good
mattress?  It is the number of coils?  I want a comfortable good
night's sleep with no backaches in the a.m.  Although not a necessity,
it would be a positive if it could withstand being jumped on by 4
small children.

It all depends on what you are looking for. Are you looking for
something more traditional such as box and springs. Or are you open to
some of the newer ideas on the market? Do you want firm or softr or
somewhere in between? How about a motionless water bed? It all depends
on what you prefer. Off hand thou I would suggest a temper-pedic. I
helped set up one and I just had to try it out.

http://www.tempurpedic.com/home/