I don't live in Oregon - although I have friends who have been working on me for years to move there - but I have been starting and ending trips up and down the Oregon coast since September of 1987. (That was my 1st X-USA starting at Astoria.) I won't tell you how many time since you might think that i'm not quite right.
Like many, I think the southern coast is most spectacular, but it isn't convenient for a cross state tour. The middle coast has some wonderful sections - esp. from Depoe Bay south to Heceta Head. But the coast near Florence is level with dunes - not the ragged bluffs and rocks so typical of the Oregon Coast. The north coast has some great sections, too - Oswald West & the Three Capes. Pretty level near Astoria, too - unless you cross the Columbia to Cape Disappointment in Washington.
I've started/ended many trips in the Tillamook/Cape Lookout/Pacific City area. Tillamook has all services, plus a nice cheese factory. Pacific City is a funky little coast town with the essentials. On my X-USA trips, I have always wanted to have a day on either end to take in the coast. YMMV - but I like to get the feel and smell the salt and see the sun rise or set on the water.
Here's a trip inland from Pacific City recently -
I connected with the TransAm at Sisters after crossing Santiam Pass. Even if you took the designated TransAm, you would probably have to use Santiam Pass in June this year instead of McKenzie. Another option is to rougly follow US 20 from Newport (maybe Yaquina Head Lighthouse - cause the feel and the views are superb) thru the college town Corvallis to Santiam Pass. On this trip I cut off from the TransAm at Austin Jct. and rode thru the Sawtooth Mountains in Idaho. There are some fantabulous hot springs that your chauffeur might enjoy.
About my pix - I don't know for sure where any of them are any more. My electronic filing methods seem to have copied my paper filing methods - which were limited, at best.
This pic - Sawtooth Mountains near Stanley in late June, 2004.
Best - J