method for altering installation location

[Andy Falanga (afalanga)]

How does one properly make a build system install to the 
system-preferred locations for 64-bit binaries?  I'm wondering how to 
properly make my build system choose "/usr/lib64" over simply "/usr/lib" 
when configure is run.  I know this can be done simply via 
"--prefix=/usr --libdir=lib64", and maybe this is what it should be 
(along with some type of bootstrap script).  I was just wondering if 
there are already elegant/"smiled upon" methods for doing this in 
configure (i.e. configure.ac).

Thanks,
Andy