One of my favorite things to do in Oregon is take the ski lift up Mt. Hood, but I've only done it in the summer. If you're landing in Portland but up for a long drive, Mt Saint Helens is also worth seeing and, in the opposite direction, Crater Lake is big as well. Portland and a lot of the things in the city itself are a miss, imo, but there is a zoo there and the surrounding forests are nice. Great views from Pittock Mansion as well and lots of waterfalls, if you're into that too. Multnomah in particular is very popular.

Gas is currently around $4 and OR is one of the few states where you're not allowed to pump your own, so you often have to wait in lines to have someone else do it.