Lake of the Woods in August
Are you taking your own boat? The big lake can get rough. Most of the action is in the Oak Island area on the MN side. We usually take a charter one day. The other days we will fish closer to the resort if the weather doesn't permit. It's not often we get out on the big lake, 2-4' waves are common. We have our two sons with and a twenty plus mile boat ride through 4 footers is not my cup of tea.
If your resort is on the river, that stays fairly calm. If you intend to fish the main lake, staying on Northwest Angle would make a lot shorter boat ride.
Honestly, I would just take your son into the Canada side. IMO it's a better experience. The fishing is much more varied and calmer water. We crossed big water in 5-7' waves, which was pretty hairy, but when we got to the lodge we were fishing in 2' waves. Your boat rides to fishing will be much shorter as well once at the lodge. We went through Reel em Inn. The food was great. A guide will go out and any boat that wants to follow them can and they will show you where to fish. When you're comfortable you can go on your own. Good Luck
If you're looking for more "hands-on" fishing that time of year you may want to check out Rainy lake. You'll be rigging, jigging and pulling bottom bouncers with blades for eye's, and the smallie fishing can be good casting early and late and bobbering leeches during the day.