If you're looking for some top things to see and do in Long Beach and surrounding area, you can visit Phu Quoc Prison and Sao Beach.
If you're spending some time in Cua Lap, Phu Quoc Beach and Suoi Tranh & Suoi Da Ban are top sights worth seeing.
Though Khu 6 might not have many top sights, you can venture to the surrounding area to see attractions like Phu Quoc Night Market and San Van Dong Duong Dong Stadium.