Seattle to Portland in December 2016

[petaleahy]

Hi!

Looking for some advice on scenic driving routes from Seattle to Portland (return) for mid-December 2016.

We are starting in Vancouver and travelling to Seattle and then on to Portland (returning to Vancouver).

I have Googled some inland routes but unsure if they will be possible as I understand that some of the roads and sights may be closed due to it being Winter.

We have no timeline but had thought we would spend about 3 days in each area. We will be travelling with kids so frequent stops and things to do along the way are important.

Columbia River Gorge is very high on our "to do" list as are the Oregon sand dunes.

Any advice for this Aussie family would be greatly appreciated!