Closest airports are Florence and Pisa.
By car from Florence airport: follow directions to Pontassieve, then to the Consuma Pass and continue down to Bibbiena/Poppi. About 1,1/2hours. Otherwise take the A1 motorway south exiting at Arezzo then head towards Bibbiena/Poppi about 1 and 1/2 hours.
By car from Pisa airport: take the Firenze Mare motorway to Florence exit at Firenze Sud and take the road for Pontassieve and Consuma Pass or continue on A1 motorway towards Rome exiting at Arezzo.
From Arezzo there is also the local railway LFI that arrives in all the towns of the valley.
The best way to reach all the discovering corners is the car.