I think you're on the right track. Again, forum rules don't allow us to link to another travel site. Try to look for back to back 7 night different itineraries. Example, on my most recent cruise, that ship (Freedom of the Seas) does the Western Caribbean one week, then the Eastern Caribbean the next week.
I'm not sure if there are any ships in RCI's fleet that do a 14 night Caribbean cruise.
2007 - Majesty of the Seas
2009 - Enchantment of the Seas
2010 - Freedom of the Seas