you are going on Holiday? your photos should be important and not add to the stress of a holiday
Take a backup of your photos as you travel, store them on your laptop and also on an external disk. Practice good physical security and keep them separate where possible, (if you leave the laptop in the hotel, take the disk with you)
Use Dropbox, it will do exactly what you want, but bear in mind that you will be uploading 1.5GB of photos a day (5MB per photo assumed), so that is a lot of data to send on sketchy wifi links and you may end up not being able to send them all back in this manner.
An effective way to make sure they are all sent home, is to burn to DVD every few days and post them home. It will probably be a lot more cost effective, easier and quicker than sending 20GB of data back to your PC.
If you are using a DSLR and Raw, you may have up to 210GB of photos at the end of your vacation. (50MB a photo assumed)