I decided to start a thread about this as I believe it hasn't been covered. From personal experience I have discovered that the trouser length actually depends on the kind of shoe one will wear. I always measure my trousers with the sort of shoes I will be wearing them with. If I chose different shoes, the trousers feel awkward...
It also depends - IMO again - with how skinny or regular the trousers legs are. Skinnier trousers look better with mocassins and regular ones with oxfords.
What do you think?