I don't know whether the line is as important as the itinerary. Some cruises just take you through the Gatun locks at the Caribbean side, cruise around a bit then go out the same way. You should be looking for a full transit from Caribbean to Pacific (or vice versa). The remaining ports of call will probably guide you with regard to the line you choose.
I totally agree, look at the itinerary and see which suits you best also the length of time you can be away and then choose you cruise line on the basis of what it provides, what cost and what suits you. ....Neil.
You might like to check out Sea Princess as I think we saw that she goes from Barbados to Acapulco and/or vice versa through the Panama Canal. the itinerary looked very good and i think if you do the Acapulco departure, rather than arrival, you get the whole day in Barbados at the end! You do need to check this out though as I'm speaking from memory and don't have a brochure to hand!!!
Further to my previous post....it was p and o Oceana (not Sea Princess but identical!) that does the Acapulco - Barbados itinerary....my partner says I got it the wrong way round its best to begin in Barbados and then you get an overnight stay in Acapulco at the end!! sorry for the original misinformation but hope this helps!!!!
Thanks to all who took the trouble to answer, I will take on board (pardon the pun) your comments.
The best Line to go with is Cunard and the best ship that transcends all others is the QE2. However due to some lunacy by a company called Carnival she won't be going anywhere for a while. The next best option would be the 'Blunt One' Queen Victoria. However do not go across the Atlantic on her unless in a former life you were an Alaskan Crab Fisherman or a North Sea Fisherman as the motion on this blunt ship may put you off cruising for life. As a ship she simply wasn't built to cross it.