Children aged under five are exempt from the minimum daily tariff and five-to-12-year-olds get a 50% discount, so travelling with children in Bhutan doesn't have to be financially crippling. However, kids may become bored with long, monotonous drives, steep walks to monasteries, hotel buffet food and the general lack of entertainment. On the other hand, they will be immediately accepted by local kids and their families. Lonely Planet's Travel with Children has lots of useful advice and suggestions.