I love Galaxy Quest. There is a unique chemistry of some actors that I would have never thought of casting... Together. Great special effects just add the comedy factor. Space balls, while considered a classic, which spoofs Star Wars, likewise shows it's age. Galaxy Quest spoofing Star Trek, holds up far better and I could easily watch over and over.
Tim Allen always make me laugh. If you've never seen his early standup, I highly recommend checking them out. Rockwell just made me laugh out loud.
Funny, funny movie. I haven't bought it, but should.