As mentioned by others, coming down the hill from Dunlop and the Tetre Rouge Esses are amongst my favourites. I also like the exterior of Tetre Rouge - you have to go up pretty high on a steep and muddy slope, but if you can find somewhere where the track isn't obscured by trees, you'll get some good shots.
As mentioned above, the outside of the entry to Porsche curves is possible, but you need to be very tall to not get catch-fencing at the bottom of the picture. I noticed some people had step ladders with them, but given how the viewing area is on a bank, they looked somewhat unstable.
My final favourite place is an unusual one. €5 gets you onto the big wheel at the Ford Chicane. It's tricky to get good photos from it as you're constantly moving and bits of the wheel's structure tend to get in the way, but if you get it right, pictures like these are your reward:
