The rush to sanctions seems to be related more to emotion (We'll show Iran!) and less to strategy. Here are three strategic thinkers on sanctions for Iran: sanctions will be difficult to apply and probably will give the opposite result from what we want. That is, if we want Iran to come to an agreement on oversight of its nuclear program and don't want it to go for a nuclear weapon.
Negotiations with Iran will not be easy, but it would be a mistake to assume in advance, as most of the U.S. press and punditry appeared to do in the days leading up to the October 1 opening of negotiations in Geneva, that negotiations will fail.Those eager for sanctions (or sanction legislation) should also consider that Iran's position will be strengthened if sanctions fail.
Gary Sick participated in a gaming exercise to examine the players' strategies. He concluded
The lesson was not so much that Iran could "win" this game so easily; it was that the US and its allies were unable even to imagine any alternatives.Those who would have sanctions are pushing us into a box.
Kareem Sadjadpour, of the Carnegie Endowment, offers some insight into Iran's internal unrest and how it impacts the nuclear negotiations. It is very likely the recognition of the inability to respond caused by this unrest that is the reason the Obama administration has put this issue on the back burner.
All three links are meaty and well worth reading.