My dad says the same thing. He says the majority of sci-fi stories are really just westerns with a location in space. For Star Wars, I would agree with GLados that it is more a space opera. But there are strains of both.Yes it's all subjective, but some films' influences are more well known than others.
Star Wars is a space western btw.
EDIT: Also, I am going to Pacific Rim tonight (Now actually, lol, at 11 at night... My mom gave me 20 bucks so I don't have to pay ) ... Your review nudged me to indulge my brother's pleading. Though my whole family will go to something else tomorrow. But hey, least I can give everyone a review from a person who wasnt enthused about the movie and doesn't have high expectations. Hopefully it'll surprise.