Re: Question
I highly recommend the book; The Grand Tour: A Traveler's Guide to the Solar System
by Ron Miller, William K. Hartmann (Contributor)
They'll answer most of your questions.
One thing I remember them saying is that When IO and Europa are at their closest, both look about the same size as our moon does from the Earth.
Here is a question. If you were on Mars when Jupiter was at is closest, would you see it as a disk?
What about Earth from the cloudtops of Venus at their closest approach?