Align bottoms of text in controls
Another fairly simple solution:
1) Use TextBlock controls instead of Labels. The reason being that TextBlock is lighter weight than Label - see http://joshsmithonwpf.wordpress.com/2007/07/04/differences-between-label-and-textblock/
2) Use the LineHeight and LineStackingStrategy = BlockLineHeight for your TextBlock style. This will align the two at their baseline easily.
<StackPanel Orientation="Horizontal"
VerticalAlignment="Center"
HorizontalAlignment="Center">
<StackPanel.Resources>
<Style TargetType="TextBlock">
<Setter Property="LineHeight" Value="44pt"/>
<Setter Property="LineStackingStrategy" Value="BlockLineHeight"/>
</Style>
</StackPanel.Resources>
<TextBlock Text="Name:"/>
<TextBlock Text="Itzhak Perlman" FontSize="44"/>
</StackPanel>
I really like the creative solutions that are presented here but I do think that in the long run (pun intended) we should use this:
<TextBlock>
<Run FontSize="20">What</Run>
<Run FontSize="36">ever</Run>
<Run FontSize="12" FontWeight="Bold">FontSize</Run>
</TextBlock>
The only thing that is missing from the Run element is databinding of the Text property but that might be added sooner or later.
A Run will not fix the alignment of labels and their textboxes but for many simple situation the Run will do quite nicely.