I'm not big on us having to bomb them. But the question remains on what to do if we don't. I don't think there's any way you can trust the Iranian regime on any negotiated deal. They've shown they will cheat on any deal just as the Chinese do on trade, they are intent on the need for the bomb. If you think they are hard to deal with now, once they have the bomb it will be way worse.
I'm not in for nation building. The best case outcome is the regime is overthrown from the inside, but that is probably a longshot. If we bomb them and aren't down for nation building, which I hope we aren't, it is saying we are wiping out the nuclear program and just spinning the wheels on the slot machine and see what shows up in their place. In retrospect, we should have done that in Afghanistan and we would have ended up in the same place, just without all the loss of American lives and money.
There's also the longshot that suddenly the regime doesn't have a death wish and heeds the warnings and makes a settlement of giving up the program and agreeing to outside verification in order to survive.