Personally, I think 32 bits is enough for any application I'd care to run. If you need more than a few GB of memory, IMO the application is being ridiculously wasteful. But YMMV -- if some people think it's fun to debug 16-digit hexadecimal numbers, I'll quote Mr. Knightly: "I have nothing to say against it, but that they shall not choose pleasures for me."
IMO 64 bits is for mainframe operating systems. For my personal use, I prefer something... well, more personal.