We would like the ability to select two pages, possibly from seperate spaces, and merge them together with their attachments etc. intact.

If two pages from different spaces on similar topics should really be one page in one space, it would be useful for our users to choose to merge the contents together into one of the pages - or even a new third page - and then tidy up the merging errors (duplication etc.) manually afterwards. This can be acheived through copy and paste, though this doesn't take the attachments over and can sometimes be laborious if you need to do many pages.