What used to be a country which everybody believed was filled with danger and nuclear weapon lovers is, today, becoming the destination with the most exponential tourism growth in the world.
From the most hospitable people to the oldest history, stunning architecture, the most desolate deserts, green mountains, islands, and many other things, slowly, travelers are realizing that Iran is the ultimate destination.
However, since it has opened to tourism very recently, traveling in Iran is not that easy, as it presents several difficulties and peculiarities, ranging from strict Islamic rules to credit card issues and even the need to get special travel insurance.
Spring and autumn would be the best months. In summer, the classic Persian cities will be quite hot but not unbearable. The south of Iran, including the islands, should be avoided in summer, late spring and early autumn. In winter, the north of Iran is mostly covered by snow.
Iran is, perhaps, safer than your home country.
Iran is a huge country with endless awesome sites to see. If you only have 2 weeks, I recommend you visit Tehran, Kashan, Esfahan, Yazd, the Kaluts, and Shiraz. I traveled in Iran for more than 2 months.
Moving around Iran is very easy. There is a big network of extremely comfortable buses that go everywhere in the country. Alternatively, you can also travel by train but not all cities have train stations. Last, for those short in time, domestic flights are also quite efficient.