The thing is, a real classic of any genre only comes along every 3 or 4 years.
Look at the timescale of the films you've mentioned.
The years 1967-1982 were a golden period for movies and a larger percentage of classic movies come from that time.
In the meantime, if you watched one film a week, you'd still have to watch 150 films before you watched one absolute classic.
I agree that The Mist will definitely be seen as a classic in the future, I think it will have the slow-burn effect of The Thing (1982).
There have been some great films outisde the horror genre in the last few years but in these times of recesssion horror itself has become very generic, even the gore films feel safe.
The only horror/fantasy films since the Japanese boom I can recommend you check out are:
Let The Right One In
These are real quality films.
Although I've yet to see I Saw The Devil, The Woman and The Skin I Live In, which have been highly-rated.
To be honest, I feel the best genre outings have migrated to television, with The Walking Dead and Game of Thrones being excellent series so far.