biggest benefit is RAM restrictions. 64-bit has none, 32-bit is "limited"
64 bit has a restriction, its just immensely larger then 32bit.
And the only reason why x64 has this "limit" is because the technology does not yet exist to create memory modules large enough to deal with the maximum supported (18,446,744,073,709,551,616 bytes). Chances are, by the time we are able to create such large memory modules, we'll already have moved over to 128-bit or even 256-bit processors.
Anyways, I use x64 for larger memory capabilities, better performance, better system integrity and security features. The list goes on, but thos are the key factors for me.