my suggestions:
1) cost of living in a rented apartment (with kitchen) for a length of > 1 month is much less than staying in a hotel and eating out. So if you could afford 6 months regardless of costs, then you might as well spend the money for 12 months or longer living in this (equally pleasant) way
2) choose a city with easy access of transportations, train or air. For a year, you can visit a different place each month. There are budget airlines offering very cheap airfares across europe and to Africa, also train tickets are much cheaper when booked weeks in advance
3) choose a location in the city's middle-class residential area, for safety and also for good food choices (local supermarkets are much better than north american style chain stores)
good luck!