Oahe is in as good of shape as I've seen it in a few years. The numbers are better, and the size is as well. I fished both the Cheyenne River area and Bush's Landing, and I happened to have better luck at Bush's. I've also heard that north of the Cheyenne area has been strongest with good reports coming out of Sutton Bay and Whitlock Bay, especially for some better size, though there are some over 20 inchers to be had around Bush's for sure, and I managed a couple 21's the first day.
The fish are still quite shallow in the 5-10 foot range, and bottom bouncers with crawlers are starting to be most effective. The best spots seem to be inside turns on points just inside of the larger creek bays. Not too long ago folks were quite successful in the backs of bays with post spawn females, but they may be starting to transition outward now. The water levels are definitely high, and that along with the smallmouth spawn may be keeping them shallow. In fact, some of the fish I caught were gurping out eggs that I'm assuming must be smallmouth eggs.
Oahe is definitely worth a shot - as is Sunset Lodge which has recently reopened - and I would focus on Bush's Landing upward and go point hopping just inside some large bays up tight to the shoreline. Water temps are finally closing in on 70 degrees in some areas in the afternoon.