If you are traveling to Iran and have enough extra time, there are several interesting countries that can be visited. The obvious choice would be Turkey. If you fly to Iran on Turkish Airlines, you can easily schedule a stop in Istanbul and then spend some time touring Turkey. Some less obvious choices would be Uzbekistan, which is a very interesting place to visit and not very far from Iran. We can arrange a trip that includes both Iran and Uzbekistan. Other interesting places to include along with a trip to Iran are any of the three Caucasian countries of Armenia, Georgia and Azerbaijan. Armenia and Azerbaijan both have land borders with Iran, as does Turkey. You could even schedule a stopover in Russia, if you fly Aeroflot via Moscow to Tehran.
So if you are going to spend the time and money to fly to Iran, you might consider extending your trip and visiting even more places.