What are some of the differences in the races?

My wife and I would like to run one of these races but are trying to decide which one. Unfortunately, the Great Wall Marathon seems to be the most popular. I say unfortunately, because to run that one, you need to register for one of their tours. That would be fine, as we want to tour anyway, but their tours are terribly expensive compared to similar tours. (more than double $ what a similar tour would cost from another company not trying to stick it to those who want to run the marathon.

How are the other two races? Part of the fun of a marathon is having so many people around but it appears the other two are very small, but they allow independent registrations.

Any input would be appreciated.

Thank you,

Greg