I visited this WHS in June 2014. I based myself in Flims and already getting there by car made my trip worthwhile. About 100m from the tourist information centre, I bought my tickets to the Fil de Cassons. From Flims I went up to Foppa (1420m) by chairlift, up to Naraus (1843m) again by chairlift, and up to Cassonsgrat (2695m) by cable car. The return trip cost around 35 euros. At every stop there are information boards, a bar or restaurant, a panoramic viewpoint and toilets. I suggest taking your time to acclimitise at each stop to avoid any possible altitude sickness. The temperature difference from Flims to Cassons was around 18 degrees so wear layers and bring a good windjacket and good hiking boots. Once I arrived at Cassonsgrat, I hiked at the panoramic viewpoint with the UNESCO information boards and a clear view of the Tschingelhörner. From there I ventured on a strenuous hike on a trail called "Fuorcla Raschaglius" (30 minutes) and another trail called "Pass dil Segnas" (2.5hours). Although I visited in late June, it was quite cold and there was quite a lot of snow left. After spotting several marmots and alpine birds and flora, I found my way back to Cassons and down to Flims.