I agree that at this point the best option would be enhanced sanctions hopefully leading to regime change. Under this administration that is very unlikely.
It is not, in fact, the case that the military option is no longer at all feasible. The new American bunker-buster bomb could do the trick and would be available to the next administration. It is, at any rate, not available to Israel.
Another option would be to forget the nuclear installations and attack Iran’s economic and military infrastructure: military bases, ports, airports, oil facilities, power plants, etc. This either country could do. In the case of Israel such an attack could be launched from the submarines it has stationed in the Gulf. Such an attack would certainly set back Iran decades and might trigger regime change.
It also, however, might trigger increased popular support for the regime and certainly would cause international condemnation. A third military option available to both the U.S. and Israel would be an EMP attack. It would have the same destructive effect on the Iranian economy as option two but might spill over into other countries and would also incur fierce criticism as well as be a humanitarian disaster.
So all military options except the first are to be avoided if possible and the first could only happen only when Obama is out of office. Enhanced sanctions are also not going to happen until January 2017 at the earliest, unless Congress can get a two-thirds veto-proof majority for them in the Senate and also make sure that they are applied by an executive that plays fast and loose with the limitations of its constitutional powers.