I think the official number of rainy days for Seattle vs. Portland is about 20-30 days higher for Seattle, and with Puget Sound being right there, that seems about right.
The Willamette Valley that stretches south from Portland towards Salem is called the Silicon Forest because of its high number of tech companies, but since Seattle has a higher population overall, they might be pretty even with the number of tech jobs actually here in the Portland area.
Portland International Airport is easy to get to off I-205 just below the Washington State line and the Columbia River. Does he have some regular cities he travels to? If he travels to the East Coast a lot, there are very few direct flights out of Portland. But if he is traveling mostly on the West Coast, Alaska and Horizon fly directly out of Portland.
Eugene also has an airport and I believe Alaska and Horizon fly out of there regularly to some cities, but he would probably have to either fly from Eugene up to Portland and then switch planes or simply drive up to Portland to fly out.
I have not visited Bend yet (ummm... have I really lived here for 9 years and not been down there yet? sheeesh...) but I would venture a guess that there are not many high tech jobs available there, and the travel by plane out of Bend airport would be even more of a pain than traveling out of Eugene. From what I have heard, though, it's a beautiful city and very friendly.
p.s. Also, let me know if you decide on the Portland area and when you will start looking for software jobs, as my partner is a software engineer and could probably connect you with some contacts. He's at Intel right now and they are looking for a project manager for their project, but seeing as how the company just announced between 4,000-10,000 layoffs worldwide in the next wave of cost-cutting, it's probably not a place you want to be... heck, he doesn't even know if he wants to be there...