All the pools have season passes. Most have a higher cost for non-city residents. We will be rotating through the pools so I don't think we are getting a season pass anywhere. Merriam is $5, Lee's Summit is only $1 (same with KCK), Mission is $7 for adults, Olathe has a parent & tot time in teh AM on certain days that is only $3 otherwise it is $5.50 afternoon only. Overland Park is $4 for most of hte pools but 2 of them cost $5.
You can get all the information you want by simply going to the city you are interested in's webpage adn the parks & rec section. I havent' checked into Shawnee, KS or Lenexa yet.
So hopefully this will help you decide what you want to do. My kids get bored with one pool which is one of the reasons we are going different places, the other has to do with the fact that we are rarely in the same place each day.
Oh, I am a resident of OP, so the prices I listed are resident of OP and non-resident of the rest.