Bhutan's mandatory $200/day tariff caps tourist numbers, and Tiger's Nest monastery clings to a cliff above Paro Valley with three more festival monasteries spread between Thimphu and Punakha.
Rhododendron blooms across the Druk Path trek, Paro Tshechu festival in March-April, and Himalayan views at their clearest before pre-monsoon haze.
Monsoon brings afternoon rain and limited mountain views, but lower-altitude dzongs accessible and trail leeches notwithstanding, prices drop.
Best Bhutan window with Thimphu Tshechu in September, Paro autumn dzong festivals, and Himalayan peaks at peak visibility.
Crisp clear winter with Punakha Drubchen festival in February, but Bumthang Valley snowed in and Druk Path trekking suspended.