Best fishing: Cowlitz to Nisqually Delta in June?

Looking for a newbie-friendly yet productive fishing option somewhere between the Cowlitz and Nisqually Delta in June.  My brother (Seattle) and I (Portland) are looking to fish somewhere between us in early June and I'm weighing options.

I realize that the best time to fish the Nisqually Delta is in the late fall through early spring, but are there any starry flounder to be had in the summer months?

Are musky the only reason to fish Mayfield?  Does Riffe Lake have good kokanee fishing?

Where would you go?

Looking for a newbie-friendly yet productive fishing option somewhere between the Cowlitz and Nisqually Delta in June.  My brother (Seattle) and I (Portland) are looking to fish somewhere between us in early June and I'm weighing options.

I realize that the best time to fish the Nisqually Delta is in the late fall through early spring, but are there any starry flounder to be had in the summer months?

Are musky the only reason to fish Mayfield?  Does Riffe Lake have good kokanee fishing?

Where would you go?

There are no kokanee in Riffe, you're probably thinking about the Coho. Nisqually has starry flounder year-round, and early June is a good time to fish for Chinook most years in Area 13.

That's great info, workhard.  Thank you!
At this point I'm leaning towards flounder at the Nisqually Delta.

Normally American Lake has kokanee ... might have to work for them a bit to.
Want to make things interesting with some bass thrown in, look at Millersylvania State Park and the lake there.

Just looked. That's Deep,Lake. Which is a misnomer because its only about 20 feet deep at its deepest.