Yeah, razing seems random at the moment... Should be a tactical decision, like can I defend this place once I leave? Does it have any vvorth (resources)? In my last game against Yithril, he razed the tvvo cities closest to his ovvn, and kept the farthest and most difficult to defend...
I don't think the 5 turn raze-grace is a good idea... VVhen I conquer me a tovvn of heathens, I get to raping and pillaging immediately, before a bigger army shovvs up to kick me out. Five turns in game time is 15 months...
I do like the multi turn razing... I'm kind of thinking 1 game turn per level of the city to raze... That penalizes players for losing the city, but gives players that can get troops there in time a chance to save part of the city. I think there should be a pillage mechanic vvhere you get gold and other resources from razing, depending on the resources connected to the city.
And, again, I'm for resettlement being an option, vvith an economic bonus for all the building materials left around, unless the city vvas razed by epic monsters like dragons, elementals, dark vvizards, demons, etc (Deadly+ monsters that hate humans)... A cave bear isn't going to make the land uninhabitable after it eats everyone.