I'm doing civil at unsw, no complaints. Teaching and facilities are great. You can either go hard, learn heaps and become mega-employable, or cruise through on passes and credits with minimal understanding (and still get a good job...) There's a good exchange program too if you're in the mood for adventure. I've heard good things from people at UTS too, maybe go that way if you're into the one year of work experience in the middle. I'd rather finish earlier though, it's not like any civil student is going to have a hard time finding a job. Don't know about usyd.
Science double is more something you'd do for personal gratification and curiosity than as a career move, especially with such a vocation-specific degree as civil. There isn't really a lot of overlap on content. Useful vocation-friendly eng/sci doubles might be mechanical & material science or electrical & physics or enviromental & biology.