I have an older laptop that stays in our Owner's Locker so I don't have to pack one for WDW trips. I have Lightroom installed on that laptop. At the beginning of a trip, I clear the catalog and delete all photos from previous trips. (The hard drive isn't very large.) Each day, I import photos from all cameras. During the imports, Lightroom is set to put one copy of the photos on the hard drive and a duplicate copy on one of the external drives. I then format and reuse the memory cards.
On the last day, I export the Lightroom Catalog onto the second external hard drive. I set the option to copy image files in addition to the catalog itself. This is what I'll import into Lightroom when I get home. If this fails, I have the second drive with the unedited photo files. All I'd loose is any edits I made while at Disney.
One external hard drive travels in my camera bag, the second goes in a different carry-on. If by some chance both external drives are lost or damaged in transit, I always have the knowledge that the pictures are still on the laptop in storage.
Something new I'll try on my next trip is a backup of an S2 JPEG file to my tablet. I have Eye-Fi cards that are set to direct connect to the tablet and automatically transfer these lower-resolution versions of the photos. This is primarily so we can look through the photos on the tablet during the trip and on the flight home, but it does also serve as a secondary backup plan. The S2 files are small enough to transfer quickly, yet have plenty of resolution for viewing on a screen. If my tablet is able to get enough bandwidth while in the room, I have the Eye-Fi app also set to send copies of the photos to PhotoBucket. That would be yet another backup.
At home, I have a three-tier backup. I have Norton 360 set up to perform a backup of each of our computers nightly. This is done to an on-site networked disk tower. This tower is hidden away in a closet, and wouldn't be immediately found by a burglar. I then have CrashPlan loaded on each computer, which creates a continuous backup to the cloud. I also have CrashPlan set up to create a back up of each machine to an external hard drive once a month. I keep this in my car. (Yeah, not the best place to keep it, but at least it's out of the house if there's a fire.)