The Haa Valley
The Haa Valley was only opened to tourists in 2002, and as such is relatively unspoiled. Drive up to the Chele Pass which at 3810m is the highest road pass in Bhutan. On a clear day, you will have amazing views of Mt Jhololhari. You then have the option of jumping on bikes and free-wheeling down to the Haa Valley (rental costs apply). The main Dzong in the Haa Valley is occupied by the Indian Army, but it is worth wandering through the local market and have a picnic lunch on the banks of the river. The Lhakhang Karpo (White Temple) is worth visiting, as is the Black Temple. You then return back over the pass, and maybe jump on the bikes again to return down to the Paro Valley.