You may want to read the reviews of different resorts on
www.debbiesdominicantravel.com.
Personally, I have fond memories of the Riu Mambo in Bahia Maimon just West of Puerto Plata, even if I don't like all inclusives. However, this was four years ago, so you should go by more recent reviews.
Even if you are staying at an AI, don't forget to leave the resort every so often to get some of the real flavour of the country. Contrary to what a lot of the resorts will let you know it is safe and fun.
Best regards,
Susanne