I'm a Hyatt/SPG/Hilton loyalist (three-way loyalty?) on first, deliberate Marriott stay in years. Gold status from some airline program, I think.
Wrapping up four days here. I won't comment n Georgetown. You'll come here if you have reason to come. Otherwise unlikely.
Hotel has treated me well. Nice room on executive floor overlooking "beach" and pool. Pretty plush soft materials (bedding, towels, fabrics). Not the slipshod quality often found in some parts of the world. Lounge access (not sure if in rate of from status). Lounge is peaceful with view of beach, six floors below my room. Several hot breakfast and evening dishes. Not especially vegetarian friendly, but I didn't starve. Good 24 hour gym, again with a view. Staff has been kind; everyone knows my name and greets me. Main (mostly seafood) restaurant has three meals a day buffet style; lunch and dinner each US $30, pretty pricey for Guyana, but choices are limited. Long walk to anything, and not much there once you arrive.
For me, it was a good stay/place. Closer to home and much easier travel than usual (Africa) destinations, and English is official language.
Quick note on the airport: no bank, no currency exchange, no ATM. (You've got Guyanese Dollars, right?)