One thing we very often hear from journalists when a rendez-vous and a docking are about to take place in space is:
Can you imagine both spacecrafts are speeding at 28,000 km/h ( or 17,500 miles per hour or 8 km/sec or 5 miles per second)!!!

But if they were not moving at almost the same speed, their orbits wouldn't match and no docking could take place anyway.

There's vacuum in space, so no wind to give any impression of speed....

I'd reply to the journalists:Can you imagine every second that is passing by, we are all of us 30 km further away!!!!
We're traveling around the sun at 30 KM per second!!
We don't feel that speed but it is there and astronauts float inside their cabin not feeling the speed either (except when they look outside but to them it could be the Earth speeding below).

Yes, speed is relative; that's the lesson.

About GT6 and GT7, what's remarquable is the high level of improvisation that took place. GT6 could not dock to an Agena, ok, let's have it get close to GT7! The first and only time 2 separately launched (from the KSC) manned spacecrafts got close to each other.
I've often wondered why 2 shuttles never performed a rendez-vous and docking in space...(wonderful images it would have been) But apparently Houston isn't equipped with enough systems to simultaneously take care of two shuttles in space.