Another Dan of the internet has made a super cool in depth size comparsion chart of all the greatest science fiction spaceships known to man. A variety of ship sizes and their conterparts can be found here
I was surprised to see how large Bayblon 5 stuff is to the Star Trek stuff. however, Holy crap, V'ger is huge! It would be neat to see it fight the Whale Probe.
what a fun idea!