Bear, there is no guarantee that you will get to the cruise ship on time if you book with the air with the cruise line directly. I think most ships will just wait two hours for their cruisers if you book the airfare with them.
I have heard of a bus load of cruisers being left behind eventhough they had bought their airflight with the cruise line. The next best thing they do is to fly you to the next port at their expense. This happened to a friend of mine. She had to wait three nights in Puerto Vallarta for the ship to show up to the first port so she could board it. So we always have to be ready with PLAN B.
It is always best to fly in one day early if you live far from the cruise port.
This summer United had a computer problem that caused a friend of mine to have to wait two days before the problem was fixed with United airlines. She was flying to Europe and missed three days of her tour because of the delay. She was with a group tour so she had to wait with the group to fly out.
This past winter.... Jet Blue and other airlines had problems when JFK got snowed in. I never fly to N.Y. and then to Florida. I by pass this problem by flying non-stop or just stop in a airport in Florida before getting to Miami or Fort Lauderdale.
We can't give information on what companies we use to buy our cruises/air/hotels from because that is advertising for the companies.
BUT.... I will send you a private message with what companies I use.