I would also consider the pads. We are in an apt as well, and also near Seattle, where it rains the majority of the time. Our apartments do not allow animals to urinate in the grass here (they said it makes it yellow), so I would have to walk him half a mile away to take him to go potty!!! That was basically an impossibility at 10 weeks old; he most definitely could not hold it for that long. (They of course did not tell us this until AFTER we got a dog).
We have a pad inside of a doggy litter pan (we did the dog litter from petco, but our dog would NOT stop eating it, and that led to other issues). We flush the poop immediately after he goes on it, and then replace the pad 3 times a day so that our apartment doesn't stink of urine. Every time we would see him start to squat, we would pick him up and run and put him on the pad. It took a LOT of patience, but it was well worth it. Now, even if he has to go in the middle of the night, he just gets up, does his business, and goes back to sleep. He was 100% trained by 6 months to go indoors. Now if we could just get him to stop either A)peeing on his foot or B) stepping in it when he is done! (We keep some doggy wipes near by just in case he does)
What's kind of funny about this is he REFUSES to go potty outside EVER. If I visit a friend all day, I just bring a pad, and show him where I put it, and he will 100% of the time go on it. In 6 months, he has not gone potty outside once...lol...weird, I know, but it just wasn't an option unfortunately.
I would do what everyone else says and make sure your dog still gets exercise and goes for a walk every day. I try to take Bailey out for at least 30 minutes a day, unless the weather is just miserable, in which case he will just whimper over getting wet
**PS - if you do decide to go this route, and need some advice, just email me and I can send you some more tips. It was a bit frustrating at first, but well worth it once he got the hang of it