Well, that escalated quickly. Moving away quickly now.....
Anyway, I'd use the 52 take on Krypton. Along with the current versions of Zod and Supergirl (both versions of Kara have had mostly bland runs with a fist full of great exceptions so it doesnt even matter really). I'd also like to see if something worthwhile can be done with H'el; he's a self-fulfilling temporal paradox that thinks he's Krypton's salvation, even if Lobdell's two arcs with him weren't executed too well its a concept worth saving.
The 52 Maxima is exactly what we have.....but her mother, also Maxima, is pure post-Crisis and I'd like to see that whole corner of the mythos expanded into Game of Thrones in space.
Clark's early years, including his sense of alienation, power development, baseline stats, etc, are all 52. Perhaps rub some post-Crisis into it for Kenny Braverman (easily inserted) and Clark's relationships with Lana and Pete.
Martha is alive. Johnathan dies when Clark is young. My preference is natural causes (heart attack, cancer, etc) but Vyndx's involvement is fine.
Superman's early years are pure Morrison Action. T-shirt and jeans, Daily Star, first encounter with Brainiac, Metallo, Steel's origin, meeting Lex....that run remains whole and the villains there are all the 52 versions. Metallo might evolve into something closer to post-Crisis over time, but for now he's good as is.
Parasite is post-Crisis version. Both 52 Toyman (Hiro) and post-Crisis Toyman (Shlott) exist. Doomsday is 52 version; the idea of Doomsday as a virus and the kill-cloud, as well as the mystery surrounding the origin, make this far better than the last one. Bizarro is post-Crisis; including the failed, tortured and Frankensteinish original version, and the Emperor Joker, Bizarro #1 version (though a tad more serious than normal).
Current day is largely post-Crisis. Married to Lois, Jon is the new Superboy.
Steel has the 52 origin but after that his post-Crisis history, picking up at the moment John hears about Clark's death. He never claimed to be Superman, after all, but his actions were so "Superman" people believed that "soul jumping" thing.
Conner Kent is all post-Crisis. But now that we have Jon, Conner would need a new name.
Metropolis expanded cast includes the post-Crisis likes of Sawyer, Turpin, Henderson, Bibbo, (mah fav'rit!) with Shay Veritas replacing Emil Henderson as Clark's go to science-person. Emil's history, and fall from grace as Ruin, can remain in continuity. Planet staff includes Lombard and Ron Troupe. Cat Grant can do whatever over in the pages of Supergirl. Krypto is 52 version.
Lana and everything introduced in the 52 Smallville, including that creepy group of old timers sitting on the porch, remains. Along with Lee Lambert.
Clark Kent is handled New52 style; post-Crisis Clark Kent was too much of a yuppie rockstar. Clark needs to be that socially invisible guy with very few friends who focuses on social issues and is far from a award winning big name journalist. Id have current Clark be a novelist who still does reporting on his own time, pursuing the "real" topics.
Superman's personality starts out 52 (brash, over-confident, lots of swagger) and evolves into post-Crisis Triangle Era, but with the self-assurance and quiet, unflappable confidence you expect from a older guy who has his act together. No post-Infinite Crisis self-doubt or navel gazing. The seasoning and relaxed machismo of (the good parts of) post-Crisis, but with the fire-in-the-belly New52 has (which is gloriously fun).
Solar flare power remains. Maybe over time a few other abilities can work their way in, mirroring the Silver Age but not as ridiculous, with more focus put on solar energy and quantum engineering type descriptors. Expands on what Morrison did, but the drawback doesnt leave Clark human baseline, but instead Morrison t-shirt and jeans baseline. Otherwise, Clark is at a Lobdell type of planet-pushing power levels.