There are number of Tourist Attractions in Arunachal Pradesh like Tawang Sela Pass Bumla Pass Bomdila Itanagar Tezu Ziro Valley Namdapha National Park Dirang Pasighat Golden Pagoda Namsai You need at least 2 Tours of 10 days each to cover major Attractions of Arunachal Pradesh
Here are some lovely places to explore in Arunachal Pradesh
Aalo Daporijo Gorichen peak
Mechuka Some national parks like
Pakhui wildlife sanctuary Namdapha national park To cover all places you need 20 days.
Namsai (golden pagoda),
parshuram kund, etc
Arunachal Pradesh is spread mostly horizontally. plus it is hilly region so it takes time to travel. that means you will have to travel for longer time and it may take plenty of time. at least 15 days will be required.