Death Valley/ND Filters

Well, this weekend I'm headed out to Death Valley. I've never really been as good as I'd like to be at nature photography, but I'd HATE to miss out on this opportunity to take some great shots. Hopefully there will be some great sunsets, and depending on my energy maybe a sunrise or two. I was wondering if any of you had any tips or tricks you could throw my way? Maybe some creative ways to shoot a 15 second exposure of the sunset or something crazy like that . . . I'll be using my Canon 30D, and Canon Powershot SD 850.

Also, I was thinking about getting an ND filter. I don't know anything about them, but I've seen some GREAT shots taken with them. Any advice?

Thanks!