Have you considered, if you can, to run only zones on bare metal sparc or x86 ?
If you have no regulative demands regarding running single kernel, you would have zero virtualization overhead with good separation.
Altho oracle VM is fine, removing entire stack above your hardware will offer better performance, less bugs and (possibly) easier administration.
Also, as i recall, on SPARC servers you can hard partition your zones regarding licensing, but you should double check that
As for geo / DR stuff, depends... What kind of tech are you using now - synchronous asynchronous and on what level (storage, database log shipping, zfs utilities etc.)
Regards
Peasant.