I'm in the get a passport camp. My wife and I both have them and we got our DS6 one for the cruise we just took. They are easy to produce at the various security checkpoints for id. and my son loves to have one. He is very proud to show it to anyone who might ask or need to see it, even though most don't need id for him such as airport or check-in to get back onboard, but it's fun. They are not that much of a hassle to get and the cost is not that much. Print out the form online, fill it out, get the pictures and go to your local post office, about an hour tops. We are planning on travelling a lot more now that our son is older and why not have it. We put the BC's in our luggage just in case something is lost, but passports are so much easier.
and before you know it they will be required to travel most anywhere, even to the caribbean. Barbados had just started to implement the requirement, then changed it's policy, but as soon as more support surrounds it, it will be a requirement. Why wait until the scramble and fees go up even farther.