Welcome to cruisereviews! You sound a lot like us in terms of what we enjoy in a cruise. Only difference is that we have a teenaged son, so we have to go when school's out, which means we generally stick with HAL or Celebrity. As you plan to go while school's in session, you have many more choices. (And, I realize that's the problem!)
What appeals to you about the ships you've been looking at? Also, do you want to be on a large vessel (4,000 passengers) or a smaller, but still somewhat large one (2,000 or so passengers). Which ships (not just lines) have you been on previously, and what did you like and not like about them?
Sorry for all the questions -- they will help us help you.