First time cruisers are typically drawn to the 3-4 day Caribbean or 7-day Alaskan cruise whereas more experienced cruisers tend to venture off to more exotic destinations. But that doesn't mean, whether you're new or experienced to cruising, you have to follow any guidelines to where you should cruise. Lay out a world map and nearly all major cities that sit on major sea shores are accessible by cruise ship; it all comes down to defining your travel preferences and sense of adventure.
You can choose a quick three or four day cruise to get your feet wet to a 180 odyssey that will take you around the world. However, most cruises are in the 7-14 day range. Also, when you go might matter to you based on your level of enjoyment of crowds and/or weather. For example, the Mediterranean can be crowded and sultry in the summer, yet cooler and less crowded in the spring or fall.
Cruise Holidays can help guide you as to the best destination or time of travel based on your travel desires and goals.