I voted opt2 but am more 32/64bit. My game is compiled in native x86-64 and I run it on Debian. However, most parts of it are either old enough that it is still original code written for 32bit or newer pieces I've redone using things like std::numeric_limits and compiler flags to determine size limits for things.
Currently we're running our mud on a very typical x86-64 Linux and it's been like that last few years.
To give myself an occasion for some bragging (or to give you some perspective, if you like), we were able to get to following architectures: ia32, ia64, x86-64, ppc, alpha, pa-risc, sun4u, vax. So, if you support anything beyond this set, we don't care.
Considering that 32-bit CPU's are becoming more expensive as they shift from mainstream to legacy/support, I would guess more people will be shifting to 64-bit platforms from now on. I'd also guess most people NOT using Windows will be using 64-bit native compilations, since cross-compiling down to a 32-bit target is annoying. Windows folk will likely be stuck in 32-bit land for a while longer, since many of them will use pre-compiled binaries.
My test muds are on a 32-bit system, as that's my spare machine. My live but unused mud is on a 64-bit system.