I dont think we have a particularly clear picture of what Iran's strategic intentions are. Obviously they're on the road to being a nuclear power but to what end? Iranians are always quick to point out that they are not Arabs or Sunnis, they are Persians and Shiites and thus what we usually think of as the "middle east" doesnt apply to them. Unlike Iraq, which is essentially 3 different groups trapped in a failed state, Iranians have a strong sense of national identity. These factors alone mean that Iran must be treated with a different strategy than the rest of the gulf states which are largely Arab. If Iraq has taught us anything its that these distinctions mean a great deal on the ground.
Iran's relations with the world have largely been defined by other powers attacking them and not the other way around. Iran spent most of the last century being swatted around by the British and Russians, before being invaded by Iraq. Essentially the Iranian posture is more defensive than aggressive and the nuclear game could be seen as an extension of that. Iran surely sees the American forces in its neighbors as a threat and considering the tone of American leaders (axis of evil) its not hard to see their point.
The Israeli question is interesting because its hard to tell what is bluster and what is intent. Iran must know it can never hope to defeat Israel with or without nuclear arms so much of it must be seen as posturing. Its also worth remembering that the current leader was elected chiefly because the moderates fractured their support over too many parties. He is essentially a populist street preacher type who is now in way over his head. Most Iranians do not have the seemingly suicidal rancor he displays and our best hope is that they will take power before its too late. We cannot hope to encourage the moderate by taking broad swipes at the nation though, nothing unites a people like an outside threat.
Hmmm -- a voice of reason. Dangerous.