I had a set of bags from Road Gear that I used on my '03 FLSTCI which I really liked. (Sold the bags on e-bay right after I sold the bike...sorry!) They were very similar to the T-Bags shown above, only not quite as expensive. They came with a waterproof liner, so you didn't have to worry about your stuff getting wet. I used them several times to pack enough gear for two people for a week with no problem! And the roll bag is set so that you can use it without the bottom bag - it has a sleeve on it that you slide over your sissy bar's backrest, clip on a couple of retaining straps, and you're good to go!
Between the saddlebags and a sissy bar luggage set, you'll have more than enough cargo space!