Could it be NC and RI drug their feet in order to not give up any sovereignty or they were jot sure how much they were giving up. I will have to pull up their ratification documents to see what the debate was.
Yes, they were absolutely concerned about giving up sovereignty. That was true of most of the states, to one degree or another. Surrendering sovereignty was an irrevocable decision, so it was a big deal. At the very least, they knew they were surrendering the sovereignty associated with the powers the Constitution delegates. NC was basically waiting for the amendments that had been promised in several state ratifying conventions. Once Congress passed a draft set of amendments, they were satisfied (they could then surrender sovereignty, believing the BoR provided the additional safeguards they needed). Rhode Island was simply entirely reluctant. RI had refused to participate in the Constitutional Convention. Rhode Island had solved its problems during the economic depression of the 1780s by cancelling debt (thereby avoiding incidents like Shay's Rebellion). Some were calling it Rouge Island. Based on what I’ve heard said on the forum, Congress finally forced RI’s hand: ratify or the benefits of Union will be denied you.
Pauline Maier wrote an excellent book on the ratification process. She doesn’t provide a great degree of details on some states’ conventions (I think that was because some were well recorded, others weren’t; for the most part newspaper men recorded the events, so the quality of the record depended on how well they could hear the speakers). It should be available at most libraries if you want to check it out.
Here is an excellent site on the subject, though I’m not sure of the level of detail on the debates.