I was afraid that was going to be your answer, the one part of the state I don't visit is the northwest and the one thing I don't really shoot is landscape.
However, here's what I would recommend. The northwestern part of the state is supposed to be the prettiest part of the state (and I'd agree it definitely gets prettier the further you go. I would suggest getting to the Northern part of Arkansas (really above LR) and then stick to the smaller roads and be willing to stop and shoot anytime you find something intriguing. There are LOTS of little streams and creeks, and many of them are very pretty, but you'll need to be willing to pull off on the side of the road for a lot of them.
My suggestion for getting to up to Eureka Springs is to go through Heber Springs. Heber has a very photogenic mountain (there are several but one stick out) and the river there is very beautiful and accessible. There will be some fly fisherman. After leaving Heber, you'll be on smaller roads to Eureka too, which will help. According to Google maps, this will add about half an hour to the trip from Jackson, MS to Eureka Springs.
Sorry I don't have more specific advice, but there's lots to find in this state. I'd also schedule a day to shoot around in Northwest Arkansas. Do some research and you'll find some awesome stuff up there.