if you want the ultimate challenge how about win teh world cup with every nation over your career?Might try this alongside the San Marino challenge- but trust me this isn't the hardest challenge, international management with a terrible nation is inevitably harder.
you definately need south africa if you want the african champions league, apart from that i's suggest going for teh slightly less obvious leagues. e.g. for europe go for france and holland instead of spain and england as it probably would be slightly easier to get a job there and slightly more interesting as it's not teh ususal powerhouses.This seems INTERESTING !
Does anyone want to recommend some leagues?