This seems like a really bad arrangement for a supercharger. Paying a minimum of $20 just to access the changers, then paying for the electricity on top of it (assuming you don't have unlimited supercharging) you could quickly rival the cost of filling up with gas. If I were a new model 3 owner without home charger ability, I would not be very happy with this.
If you're staying at the Aqua, then it's fine but wouldn't destination chargers have made more sense?
The Grand Ave location is not a very good option. There's only two stalls there (that I've found to have issues fairly frequently). It's not listed on Tesla's website so it's technically not public and the staff will give you the boot if they need it.
Let's hope they're a bit smarter about the other Chicagoland sites. So far the options for new owners are pretty poor IMO.