Space Cowboys is at least the only Space Shuttle reentry, that was filmed inside the Space Shuttle simulator at JSC.
I quite enjoy it, especially because it is what Orbiter is about: Go play in space. You don't need a congress committee to decide what to do for fun.
Otherwise: Space Above and Beyond is IMHO one of the more underrated series, I quite enjoyed it. Firefly is better than Serenity, and Serenity is a great fun of a movie, especially because of its great soundtrack. Babylon 5 is great, and I really hate Warner for killing it. The German "Ijon Tichy" adaption is something you should watch if you can and have no problems with broken German... its hilarious and was one good reason for short nights for me (Since the German ZDF aired it at the midnight slot reserved for experimental or "underground" productions, they also aired the Sopranos at that time).
"Star Trek - The next Generation" is IMHO a must-watch, the episodes became better over time and you never had better characters in a Sci-fi series ever...
Star Gate is great, as long as you watch the early episodes in which it was only about Star Gates and all the spaceship garbage was magic. It had a strong start and lost a lot of appeal then.
"Andromeda" is some sort of hard to categorize. It has some episodes that really made me glued to the TV, others really bored me to death. Space:1999 is similar in a different way: When I was a child, it really tied me to the TV, now I find it too slow paced and sterile.
But the strongest Sci-Fi movie ever, at all times is simply "Blade Runner". Nothing ever reached it yet. Especially not Avatar, which is good brainless entertainment, but you feel it is mostly Pocahontas story on steroids for putting the 3D stuff in scene. "Sunshine" is way better, but still no match for "Blade Runner".