I can say that a helicopter return from the Everest base camp visit is perfect for you if you do not have enough time to complete the regular itinerary! I actually was on the regular tour for 12 days, but I did not want to walk back those three long days to Luka, so I found other people who were on the fly-out EBC trip and joined them. I was in the group, but my other friends trekked back with our guide Sanjiv. Sanjiv managed the helicopter seat from Gorakshep after talking to Rajesh back in Kathmandu. Rajesh himself came to the airport to pick me up, so everything was well-operated. I visited some UNESCO sites in Kathmandu in my free days, until my friends did not arrive back in Kathmandu from Lukla. I really enjoyed the helicopter ride because it was my first experience and seeing the views of the mountains from the helicopter was superb, which I can not say in words!