I've read this entire thread and I'm sure I'd learn a good deal more from another complete re-read. Naïf that I am, however, my thoughts turn particularly to the mana base and I'd like to see if we can arrive at a better consensus for a more or less ideal base here.
I assume we can take it as given that we are going to need to cast at least 5cmc Eldrazi. It looks like a lot of us are also going to want to cast spells with WW in the cost, whether Palace Jailer, Sanctum Prelate, Linvala, Keeper of Silence or something off the wall like Council's Judgment (anti-True-Name Nemesis tech). (Obviously local meta may affect the selection.)
Anyway, a mana base looking like:
looks not far off the lists that most people have posted to this thread, but seems pretty light on white mana production for that. All we have are the Lotus, the Pearl, 2 Karakas (one at a time), and 5 Plains, for a total of 9 white sources and the Lotus can only be used once. I'm pretty sure I recall seeing someone somewhere had a calculation for how many sources you needed to have a probability of p for being able to cast a spell with n of a colored mana requirement by turn t, but I can't seem to put my finger on it. Still, 9 white sources seems way too low to reliably case xWW spells by turn 4-5, which is often the point where it's cast your critical spell or die. (Or, too often, be dead already.)
Cavern obviously can help with the Jailer, the Prelate, either Thalia or the Priest, but Linvala or any non-creature spell seems like a pretty dicey and potentially serious problem.
Adding more white sources looks basically like adding Plains and that means removing the multi-mana lands like Tombs and Temples, which seems approximately equally dangerous.
So, I want to solicit your collective wisdom here. Should we just plan on avoiding anything with WW in the casting cost or does anyone have a better idea?