The % command is quite nice, and I use it to copy/delete whole loops, functions and classes.
In c++ though, you need to add a ; after your class declaration, so trying to motion over a whole class won't work with the % command.
Is there a way to get the command to carry on the motion? I guess just adding a f; will be enough, but I'm not sure how.
You can force a motion to be linewise; then, the % would include the full last line, including the trailing ;, for example yV%. Unfortunately, if you use the matchit plugin, that doesn't work any more, but you can instead use visual mode: V%y (interestingly, this is the reverse of the above!)
Alternatively, you could define a custom motion for that.
