How do I stop my iPhone from connecting to the WiFi connection that my laptop just used?

Let me give you an example. I'm at a United lounge at O'Hare Airport right now. They have WiFi here but it requires that you log on in order to connect to the internet. I connect to WiFi from my laptop. All good. Then, immediately, my iPhone connects to the same network. But because I haven't logged on from my iPhone, I can't get online. This kills the internet on my iPhone because I'm connected to a network with no internet access. If on my iPhone I "Forget this Network" and then come back next week, I'll find that it connects to the exact same network.

I travel a lot and almost all of the networks I use on a daily basis require a login of some sort.

I could turn off WiFi but then I have to remember to turn it on when I actually do want to connect to a network, like when I'm at home.

Any idea how to prevent the mirroring of WiFi connections? Or at a minimum make sure the "Forget this Network" option actually works?