Blockend, I posted OT asking for experiences, didn't think I'd have to teach about the cloud. Plenty of teaching is available via Google.
Cloud storage is nothing but on-line access to redundant file system.
Don't know why OP is not realizing what Flickr is exactly this.
It allows simple and controlled upload, tags, albums, non-visibility and to be any size.
Blockend,
Guess you didn't read the OT...I mentioned Flickr there.
So you know, some cloud front ends are optimized for file searches and for downloading for printing...that's where Flickr can be inadequate.
Do you use Flickr to store your backups for later printing?
As well, typical cloud systems work as well with written material, music, technical/graphic work, and videos as with photos.
I don't know about you, but I have business and personal info as well as my own audio recordings and various email records, as well as photos, on hard drives now. I'd like to back them all up in the cloud. Flickr isn't up to that kind of task.
If I only wanted someplace to show photos online I'd use Zenfolio or similar, rather than Flickr. Are you familiar with Zenfolio?