I'm going to be an outlyer, but most of these were paired with a second event in the same region (eg MVP Summit, SQLBits, etc), and I was speaking at the SQL Saturday
Vancouver:16 500km (paired with MVP Summit)
Iceland: 11 000km (paired with InsideSQL)
Dublin: 9 500km (paired with SQLSkills training)
Vienna: 8 400km (paired with SQLBits)
Cape Town: 1300km
Durban: 600km
Johannesburg: 14km
If I was attending, not speaking, I doubt I'd go to any event other than Johannesburg.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability