Have never stayed there but have visited and Ocean Blue seems to be a comfortable beach resort. If you are looking for rest and relaxation, buying a week at an all inclusive resort does make sense.
October is a good month because it is not too hot, also rates are cheaper because it is an off peak month. Actually, October is my favorite month for travel. The likelihood of a hurricane at home is low, and the rates are better at most hotels abroad -- same as in DR.
Re mosquitos... The hotels fumigate, but in the early afternoon if you are going to be sleeveless, or in shorts, dress, you should use a mosquito repellent.
Go to our travel page (see the travel button on the top) and check out Punta Cana, La Romana areas for other options of what to do. You may consider heading to Santo Domingo for a day.
http://dr1.com/travel/index.shtml