Just to follow up to this after some research (for future readers).

If you're already willing to spend on premium cabins, mileage cards (or cards that transfer miles, like CSP or SPG AMEX) are a great value. Miles rapidly become worth more than 5% if this is your usage.

PassPlus personal is also a great option. $50k appears to get you GS, and that reflects $12.5k pp for a family of four. If that's already being spent, it winds up being a significant set of benefits, plus the discounts on airfare, and if you want to chance it, a decent chance of upgrades.