...(allies - opponents)?
Thanks to reader Phillip for the great question. I cannot answer this authoritatively. All I can say is that for the most part, the Iranians I met do not like to see themselves as part of the Arab world. They are fairly racist against Arabs, claiming that the Arabs have no culture.
The Arabs I met in Iran also seemed to find Iranian culture foreign and odd. "This is not an Islamic country," they would tell me. "Every Iranian party has alcohol. At private parties, the women remove their hijab!" Yep.
An Ahwazi Arab-Iranian told me that during the Iran-Iraq war he dreaded hearing the propoganda from both sides. The Iranians, he told me, claimed that the Arabs were dirty and blood-thirsty and the Arabs claimed the same thing about the Persians.
After an earthquake in a Sunni-dominated area, the Iranian government refused to accept aid from many of the Sunni Arab countries. Why? They were afraid that the aid would come with radical ideas and were afraid of the radicalization of the Sunni population. This angered the local population because they felt that they were being denied help... but it did not radicalize them.
I think relations among Iran and the Arab/Muslim world are very delicate. The alliances that exist are not very strong. I have actually heard people in Iran argue that they would be better off forming an alliance with Israel. (Not that we will see anything of the sort anytime soon).
The Persian Gulf States
(I hope to add more as I find them. If readers have suggestions, please add them. Thanks)