Ahhhhh… one of the most beautiful places on the planet. I'll be there the week after you but probably won't fish much, sadly,
Broken Bow is full of big bass… It held the state record for a while. It's been very hard for me to fish… I think because I predominantly fish stained/shallow water, and BB is very clear and often fishes deep, especially in the summer. I don't have a ton of experience on the lake, but here goes.
Water should be in the mid-70s when you're there… which should be good. Considering most of the fish should be post spawn, I'd avoid the main lake and treck up into the long, remote creek arms that the lake has so many of and look for areas adjacent to spawning grounds. I'd expect to find fish in the 10-15 foot range, but spend some time scouting and looking for baitfish. Graphing some baitfish balls should be a good indicator of the active depth. I'd focus on secondary points, and any brush structure you can find. Think cranks, plastics, spinner/chatter baits, A-rig, and jigs.
If all else fails, stop by the Fast Lane on the north side of the town Broken Bow (on 259) and ask for Jerry (I think). He's hard to find… but if you bump into him, he's a wealth of knowledge - I went in for a bag of ice once and ended up talking to him for an hour. I've gone back several times looking for him, but he's usually fishing!
If you've never been, you're in for a treat. Even if you get skunked. Broken Bow is an absolutely AMAZING place. If you ever question there being a "higher power", this place will set you straight.
I'd love to hear how your trip goes. Tight lines!