I went to Rio in 2016 and had a blast. The media kept trying to make Zika and safety a concern, so prices were pretty cheap, but I don't think I would expect the same for Tokyo. As far as tickets went, a select amount were reserved for locals, and then everyone had to get in a "queue" online when tickets went on sale and you hoped to be lucky enough to get the tickets you want. Track and Field, along with swimming and Beach volleyball were by far the most expensive, and sold out fast. Everything else seemed to be pretty readily available. We had tickets to the soccer semis, beach volleyball, indoor volleyball, and badminton. We tried to have an event every other day so we could use the days in between to tour the cit. Beach volleyball, at least in Rio, was definitely the most fun event we went to.