Need cash when I land, best place in Guyana? Airport or places in the city?
My advice is to use an ATM for cash. The airport exchange booths have terrible rates and will take a huge chunk out of your money. The ATMs at major banks like Republic Bank are safe and reliable. You'll get a better exchange rate that way. Plus, you can often withdraw a larger amount at once, so you don't have to worry about constantly getting cash. The Guyanese dollar (GYD) is what you'll need for most small purchases.
The best place to get cash is from a bank or a licensed cambio in the city. Avoid the airport at all costs. The exchange rates are awful. You can find many cambios in busy areas and near markets in Georgetown. The rates are much better there. I always use a cambio like Demerara Bank Limited's cambio services. I get a much better rate there than I would at the airport.
The airport exchange counters are a complete rip-off. My advice is to skip them entirely and just use an ATM in the city. You'll get a much better rate and avoid a lot of fees. I used my Visa card at a Republic Bank ATM and it worked perfectly. You might want to grab a small amount of cash from the counter just to get a taxi to your hotel, but do a big withdrawal at a proper bank.
Don't ever use the airport exchange counters. They give the worst rates and have the highest fees. Your best bet is to go to an ATM in Georgetown. Look for ATMs from major banks like Republic Bank or Demerara Bank. They are generally reliable and will give you a rate much closer to the interbank rate. Some places will accept US dollars, but you'll get a better deal using the local Guyanese dollar (GYD). So get some cash out at a bank ATM and you'll be good to go.