Virtual Machines

So, I was thinking about virtual machines, specifically about extending a 32 bit virtual machine to have access to more memory by segmenting the memory. Now, the 8086 supported 1 MB with a segment selector offset four bits, so each segment differed from the one preceding it by 16 bytes. I was thinking about having the segment selector offset 16 bits, supporting a 48 bit memory space and making adjacent segments differ by 64 KB, or I could offset it 24 bits and have a 56 bit memory space, with segments differing by 16 MB. Which is more useful, larger or smaller segment differences? Should I just make each segment distinct, allowing a 64 bit memory space?

It's already possible for a 32-bit machine to access for than 4GB using PAE (you're then stuck at 64GB, though). On windows there's also Address Windowing Extensions, which allows a 32-bit program to access more than the usual 2GB of user-space memory.