Lifetime Premier Gold is going to be worth a lot more than it used to be given that the ranks of Premier Silvers are probably going to thin out and won't be taking up E+ seats.

If you don't foresee yourself hitting Premier Silver, I'd just pay ala carte. The Premier Travel option gets you 2 bags, E+ assignments at the time of booking, Premier boarding, Premier security line, Premier check-in, and (not sure on this one) priority luggage.

Or you can apply for the MileagePlus Explorer card, which has benefits similar to Premier Silver with the exception of E+. You could then just buy the E+ annual option.

1MM is still definitely going to be worth it.