I want the client window to fill up the whole screen, except for the Windows Taskbar or MacOS Dock. Clicking the maximize button at the top right of the client window accomplishes this, but I have to do it each time I open the window. It would be nice if there were an option to open the window in the maximized state.
Thank you for your feature request. It sounds like a use case we should consider in our development plans. It is not a request we've heard before though, so I cannot say when this might be looked at. Given the use case it might also be sufficient to solve this with a tweak to the reconnect behaviour. I.e. if you disconnect a session whilst maximized, the client might be able to figure out it should be maximized when it reconnects again. This would fit well with our existing approach where we mainly try to follow the size of the existing session. We also need to take care when implementing this and to test extensively. Window positioning is generally the window manager's domain, and not something an application should fiddle with. There are many corner case where we'll get odd results.
In 4.13.0 you had the "Work area (maximized)" option in the Screen tab. That's what I was using, but it is no longer is available in 4.14.0. So I'm going back to 4.13.0.