Well imo a WDW vacation can be done more cheaply than a DLR trip especially on a per day basis. But, it can also be wayyyyyyy more expensive in your per day and probably will be more expensive in total if you don't count air fare.
Some General things.
1. Being in Portland, airfare to Orlando is going to be more expensive than that to one of the LA area airports. Also, given that LA has 5 airports as viable options, you can sometimes find a great deal into one of them. Orlando has only the one option. Tampa is in range but you'd have to rent a car if you flew in there probably negating any cost savings of doing so.
2. Doing WDW, and seeing most of it usually requires a week at least. Mk takes a couple days, Epcot takes a couple. AK and DS each take one. That's 6 days. You could easily spend a day each in the water parks plus a day to do Downtown Disney. And if you go to one of the hard ticket events at MK, well you'd do Disneyquest that day and get ready for the party afterwards. Well you're up to 9. Throw in a day of shopping and stuff at DTD or bumming around the resort and you're up to 10 days. You're still up to 7 with just the main parks. Well as you've surmised, 7-10 days of food lodging and tickets are going to run more than 3-4. And we haven't even gotten to Universal or Seaworld yet. And note that most on the WDW boards will tell you DS and AK can be done in 1/2 days each. If one has been there awhile or just doesn't want to see everything, that is probably true. But for a first timer who wants to see it all including the parades, they are both going to take a full day. .
3. Disney has value and moderate resorts there on-site that are far less expensive than those at DLR. And the values are cute. However, they are big and it can be a long walk to the bus stop. A couple of the mods are so big they have multiple bus stops. The values are no-frills though. And some of the off-site hotels across the street at
Disneyland will cost you about the same as a value at WDW and the rooms themselves are bigger at the hotels across from Disneyland. But the values are very cute and we're satisfied with our stay in them. Note that these are 10-15 minute bus rides from some of the parks. If you want a resort on the monorail or in walking distance to epcot, prepare to shell out some bucks. However, some of the better rooms in the deluxes will cost you more than at DLR.
4. WDW usually offers better discounts than does DLR. So if you're flexible about when to go, you can decrease the cost of your trip. For example, the last two years they have offerred a free meal plan for arrivals in late August through September. We saved about $1200 doing that. Note we ran up total tabs on the meal plan to the tune of about $1800. But we wouldn't have run up those kind of tabs were we paying. So we ate better and saved about $1,200. They also offer
AAA discounts on the rooms which can be substantial.
5. Once you get up to about 6 days worth of ticket, extra days cost you about $2 each. So the longer you stay, the per day cost of tickets go down.
6. Disneyland is all walking distance. WDW isn't. Many people insist on renting a car as they don't like the buses which can get to be Standing room Only, especially during the mass exodus after the firework shows or Fantasmic. Of course renting a car for a week can be expensive. I myself drive down so we don't need to rent one. We find the busses fairly convenient and instead of packing the lines like everyone else after the fireworks or the shows we do our shopping then or just leisurely sit. Disney is fine with it. They're fine with you easing the crunch on the buses for about a 1/2 hour or even longer, ESPECIALLY IF YOU'RE BUYING SOMETHING.
So you see it all depends upon when you go, whether you can get a deal on airfare or a package, what hotel you wish to stay in, etc, etc.
Go to their website, and start putting in your requests, and see what they come up with. I did that and then found out 
Anymore questions... fire away!
