We have purchased trip insurance through Travelguard a few times, and placed a claim twice.
If we are flying and traveling with family members from multiple households, it makes sense to us to purchase it. If it's just our immediate family and we're driving, we skip it. With a Disney trip, you can cancel at the last minute and reschedule for some date way off in the future and it only costs a $50 change fee. Of course, if something happens DURING your trip, trip insurance can be beneficial.
One time we put in a claim because my Dad had a detatched retina 2 days before our scheduled trip. It was nice to have the insurance, but honestly, we didn't need it. We were flying Southwest, where you get the price of your airfare back as a credit that is good for 12 months, and we could have simply rescheduled our Disney stay for $50. It was nice to get the cash back for the airfare portion, but we would have been okay with the 12-month credit for travel directly from SW. Disney refunded our full package cost, minus $200 for canceling at the last minute. The insurance paid us that $200. But we had paid somewhere around $150 for the insurance in the first place. We came out ahead, but barely. HOWEVER - if Dad's retina had detached a few days later while we were already ON VACATION - it would have been a whole other story. He would have had to be treated in FL and stayed put unable to travel for a few weeks. THEN the insurance would have been INVALUABLE.