Why limit yourself to only one hotel program? Haven't you ever gone anywhere where there's no HH propoerties (or the HH properties don't meet your needs)?
How about a Chase IHG Club MC? For a meager $49 AF, (after the first year), it gives you
an uncapped free night certificate (after the first year). (The first year it gives you a bunch of hotel points if you do the minimum purchases.) And while you hold the card, your IHG points never expire.
You could use the card only where Amex isn't accepted,, and only stay at IHG once a year with that free night certificate, plus when it just makes more sense with the points you'll get the first year.
Or, if IHG it too similar to Hilton Honors, how about a lower-end hotel program (which is
all you'll find in many smaller towns), such as WyndhamRewards or Choice Privileges?
Also, keep in mind that many hotels transfer to Delta, even though nowhere near at the earning rate that you get with a Delta card. But if you're only going to use the MC/Visa where Amex isn't accepted, and if you're not interested in any other hotel program for hotel points as such, consider a hotel program for transfer to Delta.
Hotel programs are
the only non-Amex ways to transfer to Delta that I'm aware of.