I'd generally be much more inclined to go with a simple hypercard-like stack paradigm, with manual placement of controls, and some ability to adjust for different screen sizes and aspect-ratios.
In my defence, it's a strategy game I'm working on (think Advanced Wars). As I said, at minimum I'd want an easy way to arrange widgets in a row or column inside some rectangle (a row of buttons for a control panel, a column of unit names for a unit list, a row of two or more columns of text fields in a statistics screen...). The last time I manually placed widgets in a game (rather, manually computed their locations) it got pretty tedious. Widgets with manual locations might work better if I had a visual editor, at which point I might as well integrate CEGUI or something that already comes with an editor.
That said, I've been thinking about how far I could go if with proportional positions and sizes (either relative to the screen or a parent widget).