Is there a self-directed brokerage option in either your wife's or your 401K plans? That could be a way to circumvent your still relatively expensive Black Rock S&P 500 fund option.
Different story: my wife's company recently changed 401K providers and some of their house funds have such ridiculously low expenses that I'm moving stuff around a bit to take advantage of it. This is largely because like a BONEHEAD I've had my BND holding sitting in a regular account for the past few years, and as a result I've been cutting Obama unnecessarily larger checks as a result. I had no clue that BND spits out INTEREST, which is taxed at one's highest marginal tax rate.
So now I can keep my non-qualified bond ETF/fund dividends in a retirement account and at the same time purchase a fund with even lower expenses than BND, which is almost unimaginable. I know this is way off topic, but the lesson is that there are inevitably always ways to keep on optimizing.
Good luck. Even with Black Rock, you're going to be on a better track.