convince me 
in all my experience with vassals i didn't really get them to use at full efficiency or they were always backstabbing me.
in my first game (settler
) i was far far ahead in tech, when i landed on the second continent and razed a city two civs offered me vassalage. so i figured why not, and took them.
i tried to use one of them as my warmachine, so i gave him most of my techs and some units so that he could help me fight my wars.
but what did the bastard? after 10 turns he revoked his vassalage...
needless to say i nuked him into oblivion
then the global warning started to hit in and i aborted the game, was boring anyway.
the next game i tried it a little bit different.
i brought an enemy to capitulate, donated him all the captured cities back, gave him most of my techs and used him as tech whore.
as he had capitulated he couldn't break free without growing larger or getting decimated by another civ, so i was quite safe.
problem was: he sucked at teching, so most of the time i ended up researching it myself anyway.
so far the only use i found for vassals is for a diplomatic victory, cause they have to vote for you.
anything i am missing about vassals?

in all my experience with vassals i didn't really get them to use at full efficiency or they were always backstabbing me.
in my first game (settler

i tried to use one of them as my warmachine, so i gave him most of my techs and some units so that he could help me fight my wars.
but what did the bastard? after 10 turns he revoked his vassalage...
needless to say i nuked him into oblivion

then the global warning started to hit in and i aborted the game, was boring anyway.
the next game i tried it a little bit different.
i brought an enemy to capitulate, donated him all the captured cities back, gave him most of my techs and used him as tech whore.
as he had capitulated he couldn't break free without growing larger or getting decimated by another civ, so i was quite safe.
problem was: he sucked at teching, so most of the time i ended up researching it myself anyway.
so far the only use i found for vassals is for a diplomatic victory, cause they have to vote for you.
anything i am missing about vassals?