I like the idea of a retro feel for the time period, but I usually associate 1960s design as being one or the other of two extremes: either the later part of the decade with completely hand-drawn/illustrated psychedelia, or the very grid-based, ultra-Swiss/International Style design of the beginning of the decade [which, granted, was a holdover from the 50s, but if Pale Fire is from '62, then...]. With the use of geometric shapes and primary colors, it looks like you're thinking about International Style, but I'm not sure the typeface works for that. I know there are designs from the 60s that use faces like the ones you're using, but I'm not sure they're as immediately recognizable of the era as sans serif types like Helvetica or Univers. Both of those typefaces would match the idea of using more geometric shapes. That being said, would a straightforward Swiss style design reflect the way that Nabokov is satirizing literature and the literary tradition? I don't know. I do think that it might be interesting to take the structural elements of the era in design [the grid, the ultra-uniform/geometric typefaces] and use them in some ironic way to reflect what Nabokov is doing with the preface/poem/notes elements.
I like the idea of the hexagon--I think designs of the era were more based on the rectangle/square, triangle, or circle, so the hexagon seems like a way to bring that retro feel into a more contemporary place, if that makes sense.
If you're sticking with a decorative slab or a serif face, I'd suggest looking for one with less contrast between the stroke weights, especially for the second and third design. The didone-looking typeface in the second and the copperplate gothic in the third don't seem to reference the era you're going for, to me.
If you're thinking Swiss/International Style, it might be helpful to look at work by Fridolin Mueller, or Armin Hofmann; in terms of American designers, I generally associate Saul Bass with the late 50s/early 60s, and that second design is hinting at a paper-cut style that is a little Saul Bass to me.
