Re: Irvine and Santa Ana
The 280/680 4-level intersection down by King Road in San Jose was left incomplete for a long time (three or four years, IIRC). Every Christmas there'd be a tree, lit, on the top chunk, waiting for the day, I suppose, that it would actually have traffic flowing by it (albeit slowly, anymore).
Don't forget 880 (aka 17), 85, and the host of other freeways masquerading as "expressways"
(San Tomas, Montague, etc.). The only thing missing is the express bit :)