Most of the shops still run the 32bit on the 64 bit arch. It would be better to sail with the 32bit, b'cos though the 64 bit arch. available in the market, oracle hasn't yet come up to the speed of releasing the patchsets for 64bit as that of 32bit.
If I were you, I would just wait with the 32bit and once oracle reaches its patchset release flow, I would move on to it. Only thing that you would be missing on this is that you are not making use of the OS arch. to the fullest extent.
Life is a journey, not a destination!