Bhutan isn't a country which sees huge crowds of tourists during the high season, and the key reason is the minimum package tourists fee, which is $250 per person per day. If you want to visit Bhutan, you have to pay the price. Luckily this amount covers your accommodation, meal, a licensed Bhutanese tour guide, all internal transport, and camping equipment for trekking.
Spring and autumn are considered the high season, because the weather is very favourable for all kinds of outdoor activities during this period, including trekking, biking, and kayaking. In addition, the spring months reveal the beauty of blooming rhododendrons, and autumn months become gold with rice fields, red with fresh chlli peppers, purple with Gentians, and white with Edelweiss.