As far as I know, Sage is the only rod company that gives a lifetime warranty. So if you ever break it, they'll just ship you a new one. How can you beat that? I think you'll be more than happy with any sage rod.
I've got a 4 piece sage 4 weight and really like it. It's a fast action rod, and it even handles a 5weight line really well.
To get a better idea what weight you should get you might want to be more specific about where you want to fish. If I'm fishing for pinks or coho in the Squamish/Mamquam, then I'll bring my 8 weight, and get a good fight even out of the pinks. In fast moving water you usually need to use weighted flies, and heavy sink tips, all of which are easier to cast with a heavier rod. If you'll be fishing for coho in the esturaries you could probalby go lighter. For the small trout we get in the lower mainland lakes I like to use my 4 weight, but it can be a bitch to cast in the wind. For the larger interior trout, a 6 weight is ideal. All that doesn't really solve your dilema though. I would say that if trout are your priority, get a 6 weight, but if you'll be on the river a lot for salmon you might want to step up to a 7 if possible, but I wouldn't go heavier for an all-arounder.
Oh, and get a large arbor real. They're great. I was pretty impressed with the Fenwick large arbor, especially for the price (don't remember the model).
good luck.