Banks lake is my favorite. Been fishing there with my dad since I was a kid in the 80s.
Beware, some parts of the lake are very shallow and can be dangerous with lots of rock outcroppings. If you get into some of the long stretches of the lake, it can be a real battle if the wind comes up if your boat isn't powerful enough to motor back to the launch. There is a huge long stretch of the lake where there is just not much going on, most people avoid it completely.
Lots of good bass & walleye in the rocky areas around Steamboat Rock. Probably the best area of the lake to fish in.
If you have a bow with a spool, there is some good carping to be had in the shallow areas, especially around the old road bed which is saturated with reeds. Some of them are just absolutely huge.
Steamboat Rock has a big state park with facilities and a launch. There are also couple of great camping spots around the lake only accessible by boat, with sandy beaches and little private coves. When you go ashore, watch out for rattlers..
Also just past the Steamboat Rock public launch there is a trail entrance to an old homestead property that was deeded to the state - called Northrup Canyon. It's a nice hike and you can go really far back into the canyon, where the trail ends up at a small lake. The old homestead is still there intact.
Lake Roosevelt (Columbia river before Grand Coulee Dam) is also just down the road. Not a huge fan of fishing there due to currents and wind, but there are some coves that are populated.
Don't forget to check out the laser light show at the dam. The new show is sort of hokey and a little too PC, I preferred the old 1970s one, but it's still a great show to see the spillway open up on the dam with the lights shining onto it.