I'm not sure that I understand the second option.
Anyway, I'd go with option 1, using a switch.
The second option would be to create (if it's possible) three separate VMotion connections, one to each other server. If this is not an option then this option goes out the window.
My reasoning for this option is because the hosts have 10GB nics, but I don't have a 10GB switch.
I would buy a 10 GB switch. And personally I would always create a slightly larger subnet then I need at this moment... So in your case create a /28 subnet. This will give you enough available IP addresses.