Personally I'd just go with a straight 3% or at least 2.5% cash back card (on all purchases; dealing with category bonuses IMO is not worth the hassle...may be for someone like the bloggers it is, but not for most). It's rare for any travel-specific program (airline, hotel) miles, points or what not to exceed 3cpm value. That way you are not tied to any airline or hotel, there are no blackout dates, no constantly decreasing value of the awards, etc., but if you prefer you can still use the cash-back as travel purchases offset - while being completely liberated to use it for whatever you want.

Edit: sorry, I missed it that you want it to be an AmEx (but why? AmEx has some of the worst service, and is not accepted at many US businesses and most int'l ones). For an AmEx card, well just get the straight up Platinum AmEx. Priority Pass lounge access, Uber credits, airline fee credits, etc. - if you use it all, you can almost justify the annual fee. Just the rewards in terms of MR are subpar, but, well, that is the best that you can get with AmEx, unless you go with the SPG AmEx that has the most valuable (transferable to almost any major airline) rewards, but the fate of the SPG program in 2018 and beyond if uncertain still.