Piece of cake
If you are arriving at Santiago airport (STI), you have two options:
1) [a]Take a cab from the airport (ask for Rafaelito, he's a good man) and get to either Metro Tours or CAribe Tours--Los Jardines. They are on the same little street. Fare should be RD$350 ($8.50)
Take a bus to POP (RD$200) Stop some place on the way in from the airport that says "CAMBIO" and change a few dollars.
[c] Take a cab from the bus stop to the hotel in Playa Dorada
2) Have a cab waiting for you at the airport and have it take you directly to the Hotel. this will cost about $30-35 dollars.
If the latter, send me a note and I'll set it up.
HB