A favorite of ours that we keep going to is NkMip RV park in Osoyoos. There is full hook ups including 50A, free wifi, great washroom and laundry facilities and reasonable rates. There are lakeside sides on Osoyoos lake which is super warm and great for swimming. We stay in an area away from the lake but it is only a 5 minute walk through the campground to the lake. The great thing for us as well is that they are big rig friendly. It is also far enough from the highway that it is quiet.
We were there for 2 weeks this summer and have already booked for next summer.
We have also stayed at Swan Lake Resort which is beautiful, however it is fairly close to the highway so it is a bit noisy. They also have sewer holding tanks that must be pumped out daily so the pumper truck showing up at 8 am every morning became a bit old after a few days.