hi Joyce
Since i have been going to the DR 11yrs, that's all I have taken.
Canadian or us travellers cheques are easy to exchange. If you have a passport you are O.K. If you are only changing say 100 a day, stay with canadian. There is not much difference in the out come and easier to divide by ten, then sixteen. Anywhere in sosua, capital, puerto plata, etc.. You have these small places along the road in sosua to exchange money, that's your best place, not from your hotel.
Just look and ask for the rate then take the best one.
Have fun
Royal