Disgaea has a somewhat nice function in that no move is set in stone until you choose "execute," but even this has it's flaws, depending on the enemy's reaction to your action. Plus it's kind of annoying that if you click 'back' it will move your guy all the way to starting position (for that turn). Still not perfect, but very good. I suppose a "are you sure?" would be nice for executing and ending your turn, and this is where GR:SW shines. I never finish a turn wondering if I forgot something.
FF Tactics A2 has a nice system in that you can undo your move up to the point of action, so if you had an attack planned but once you moved where you planned on moving, realized the attack wouldn't work, you can move back and to a different location instead.
I think GR:SW has a brilliant system in that you click on a character and it shows you where you can move and act, as well as who you can target. At this point you can click on a target to see where would be most beneficial for you to attack from and who can counter. It is a smooth system.
Anyway, thoughts on the 'undo move' function of this and other games?
I had to obsessively save after nearly every round in the Advance Wars titles, back before I had the game mastered; now I don't really have that issue, but it was still really annoying. An undo move function would be wonderful in most strategy games, but obviously it'd only work in single-player games and in games that don't care about trying to be as 'hardcore' as possible.
In games with fog of war it doesn't work to undo even if your moves find no new units, you have gained information. It's been awhile since I played the older AW games, but in the newest on which I'm playing now an undo feature would change the game not just be a nice convenience.