If all of you would go to the archives (hit Search button above and type in "money"), you will find a wealth of advice. On our visits to DR from the states, we have followed the DR1 advice and never had any problems. Here it is:
Take half cash/half traveler checks (for safety purposes).
Exchange to pesos "as you go". You don't want to have alot of pesos at end of trip - many places won't give you dollars back.
Your ATM/Debit cards may or may not work - even if it is in your network. Ours never has. But if you try, use a machine at a bank during business hours because sometimes the machine won't give you your card back. I don't know what the ATM fee is since our card has never worked. However, if you go in the bank, you can give them the ATM card and they'll run it through their machine. It has always worked that way.
We exchange our cash/travelers at banks only. Many times they are the best rate and we don't have to worry about counterfeit.
Refrain from using credit cards. Your company will impose about a 10% exchange fee; they will charge you what the world monetary rate is - not what the local bank or newspaper says. You may get burned on this. Also, don't use "cash advance". You not only will get the 10% fee, but also a stiff finance charge will be added that begins that day. If you pay off your credit card at end of month, you still have to pay the cash advance finance charge.