You must have some idea where you want to spend your time. In Santo Doming? in the mountains? on the beaches of the North Coast? South Coast? In areas away from tourism? If we had an idea as to where you would like to spend your time, it would help us to answer your question.
For example, if you are going to spend your time in Santo Domingo, there are budget accomodations in that price range that wouldn't require reservations. Likewise if you are in Dominican areas away from tourism. If, for example, you re talking about the North Coast beaches, then coming without any reservation would be riskier.
