In id’s Radiant you can Alt+Tab, and cycle your maximized viewport to the next. Its very convenient and you can see a lot more detail in what you’re working with instead of four smaller viewports.
Similarly to UE4/UDK, Maya has the 2x2 viewport (typically) but it allows switching between views much easier than UE4. In Maya, hitting spacebar will maximize / de-maximize(?) what ever viewport my mouse cursor is over. So I can go from Perspective to Top view in two key presses and just moving my mouse. In UE4/UDK, the default Alt-X (in UDK at least) is kind of an awkward keypress already, but I also have to click which viewport in order to make it my active viewport (never really been a fan of that the “active” nature anyways, I’ve had “Play” moments where no inputs work because I wasn’t technically clicked on the perspective viewport).
If you guys could do either or both of these, it would only make your tools even more efficient. Anyways, thats my 2cents.