Wow, I'm just home and I see I have a lot of posts and updates to catch up on
From reading the views so far here, here are two options coming to the fore about how to decide the host:
1. Vote to decide the host - like @dcro pointed out, it could result in strong feelings for those who don't secure the bid by popular vote. To counteract this we would need to carry out the voting in private and announce the winning bid without giving any details about the vote breakdown (similar to TISC award for best user voting).
2. Random game of chance - everyone has an equal chance of hosting. I guess it could be tweaked to weigh the random chance slightly in favour of those bidding nations that did not host before but those such as Mexico and Serbia too have their chance. So if was another key game like the one we had for TISC Annual 2015, those nations who are bidding to host for the first time could start with 1 key each and all of those who hosted before would start with no keys before the "key search" takes place.
Thoughts?
I must say it is very exciting to see so much interest!