My friend and I participated in the Navy Pier Fireworks tour on Labor Day weekend. When we arrived, we had the option of two single kayaks or a tandem kayak - the tandem kayak was a little bit more effort to coordinate (we have a little kayaking experience so perhaps we were better than average), but it made it easier for us to stay. Lose to each other than if we had chosen two singles.
It was a pretty large group - about 25-30 kayaks - but there were several tour guides interspersed throughout the group. Chicago river is super busy and crowded, so I was glad we went with a tour, rather than on our own. The tour guides were great, like camp counselors: the perfect mix of fun and safety.
Due to the number of kayaks, it was a little crowded in the middle of the group. My friend and I just made an effort to stay near the front, which was much less crowded and much more pleasant. Some people didn’t have a lot of kayaking experience, which was totally fine - the tour guides teach you how and watch over you! - but other people would occasionally run into our kayak, which we didn’t like. We didn’t want to risk falling out!
Overall, would recommend. Got there at 8:30, was done around 11. Quick note: be prepared to get wet. The oars just naturally drip water when you switch paddling sides, so you will be wet by the end!