Although small in size, there is always plenty to do in Rhode Island no matter what time of year you visit. The winters can be very cold and windy but attending the winter festivals and seeing the holiday lights in Newport can make dealing with even the coldest of temperatures worthwhile.
Summers in Newport can be quite crowed so you may want to visit in the off-season when the crowds have gone home and it is less difficult to get a reservation in the restaurants. Prices are much better in the off-season as well.