It has been 20 years or so since I've been there, but Fillenwarth Beach is family owned and prime location on West Okoboji:
fillenwarth beach - Google Search
It used to be a bit pricy, but you have to factor in the prime location right on the lake and close to everything in Arnolds Park and other amenities like sailboat rides (and maybe even lessons?) and the daily "booze cruise". Huge dock and you are on the east side of the premier lake, so the sunsets are outstanding. The family is nice and the guests are friendly. If too late to get one of the units right on the lake, they have cabins just behind the main building, with all the amenities. The smaller units right on the lake are probably best for two, but I'd consider any others in your price range just to get there. I've camped before too, but this is a really excellent location, and again, all the amenities. It is a short walking distance to all of the major things in Arnolds Park.
Not sure about weekend only. We always stayed at least a few days, or maybe a week.