This is a tricky one. As you say, both have pros and cons. If you just want to relax to the max then I'd say a resort is better because you can spread out more and find a quiet spot somewhere on the beach, by the pool, etc and there are more things to do like golf, etc and you can go and explore the island, etc. HOWEVER, a lot of these resorts are very much couples/honeymooners only (which might be what you want!) but be prepared for a lot of people, young and old, who are in the mood for LURVE. Check also about weddings - some of these resorts have several weddings a day and they can be quite disruptive if you can't get away from them or if they take over large sections of the hotel, pool, etc.
Cruising means you get to see more places, although the excursions etc can be quite hectic and 'touristy'. You won't have as much personal space and there are always people everywhere. There's more entertainment provided and the catering is usually superb and some people enjoy the ritual of dressing up for dinner every night. But it's a worthwhile experience and a bit 'different' especially if your husband hasn't done it before.
In my experience, one Caribbean island is very much like another in terms of the standard of resort and facilities provided and you basically get what you pay for so it's not something I'd do on a very limited budget to be honest. Ditto cruising. Bugs are bugs wherever you go so if you freak out at anything with more than 4 legs then perhaps the Caribbean isn't for you anyway.