For 50 nights per year, including free nights, Hyatt no longer makes any sense.

I'd suggest focusing on SPG. A credit card gets you Gold easily, which becomes Gold at Marriott through status match and gets you lounge access at Marriotts. On the Starwood side, you currently need 25 stays or 50 nights (including free) for SPG Plat and Starwood lounge access, etc. This would become Marriott Plat too, but Plats are basically treated the same as Golds at Marriotts.

You can get Hilton HHonors Gold through credit cards, such as the AmEx regular Platinum charge card. Diamond requires more and IMO would be lower priority than Starwood > Marriott status.