#4 -- "Against the Day" by Thomas Pynchon
Well, that was a haul. And a good one -- it's a great book, maybe the most purely enjoyable Pynchon other than "V." After the pre-read reviews, I was expecting something much less cohesive, but this was considerably more linear than most of his books, I'd say.
It helps that he draws on several Greg interests here: Colorado mining, the Tunguska incident, Balkan intrigue. All it needed was hockey.
It's not perfect, by any means. As previously noted, the higher math stuff lost me. Then the pace really seems to drop off in the penultimate hundred pages. But in the end, man, what a blast. Amazing ideas at work here -- and I wonder if I'm alone finding it, once I got through it, to be Pynchon's most hopeful novel.
Anyway: a few Hardy Boys books after this, probably. My brain needs a rest. Glad I finished it on the last day of vacation, at least.