If you are on a budget, you might want to stay wawy from disc brakes. They are more expensive to start with and to maintain, especially if you want to do your own repairs. I suggest looking at cross bikes. I agree that hybrids aren't all that good for long riding (like Portland to Seattle). Something with dropped handlebars is a good idea.

Be sure to leave enough space in your budget for the incidentals, which can exceed the cost of the bike if you're not careful. You will want a frame pump (with a flexible nozzle, do NOT get a fixed minipump), basic metric tools to work every bolt and screw on the bike, spare tubes, tire levers, a patch kit, possibly a rack (although you can upgrade to that later), fenders (although you can buy those later), rain gear, shoes, lights if you will ride when it is dark, etc. Oh, and a seat bag to hold all this.

I use a surly cross-check, which I bought $750 stock built (minus pedals) last fall, but some folks have said the price has doubled in the last year. I use it for commuting and long weekend rides (20-100 miles). Surly also has a Long Haul Trucker that just came out. It might be better suited for what you want, but I haven't seen any prices for a built-up bike. My guess is it is out of your price range.