Attack of the 50-Foot Woman (1958)
The Blob (1958)
The Creature from the Black Lagoon (1954)
The Fly (1958)
The Day the Earth Stood Still (1951)
The Thing From Another World (1951)
Earth vs. The Flying Saucers (1956)
They have lots of information explaining their choices.
I've seen Attack of the 50-Foot Woman, The Blob, The Day the Earth Stood Still, The Thing from Another World and Earth vs. The Flying Saucers, which can be viewed online at those links.
I've also seen Creature from the Black Lagoon and The Fly, but I can't find them online.
They also suggest:
Invaders From Mars, Invasion of the Body Snatchers, It Came From Outer Space, When Worlds Collide, The Day of the Triffids, Plan 9 From Outer Space, and Killers from Outer SpaceOnes with links are ones I've been able to find online.