Could someone share some tips about what to see in Sumatra? We are mainly interested in the nature and culture, to see how people live in villages. We would also like to visit some national parks and do a few days trekking there. So far, we have been looking into the options to visit Gunung Leuser national park, Kerinci Seblat national park and Mentawai islands. However, it writes on internet that visiting national parks is not allowed without the guides and prices (at least in travel agencies that we find online) look crazy high. Anyone visited any of these and could share the experience? Are these worth visiting? Can those be done independently (without a guide)? Any other destinations you could recommend, especially off the beaten track (if there is anything like this remaining :D)?
Thanks in advance!