Syntax aware selection (Ctrl-W) doesn't work for you? I know it's not exactly what you ask for, but I think it's great. It successively selects a bigger and bigger block of code. According to Productivity Guide, it's the feature I use the most in IntelliJ (by a wide margin).
There is an editor action to select a line (Select line at caret) in the keymap that doesn't have a default shortcut, but you can define it and use it instead of the first Home+Shift+down. Then you can extend the selection with Shift+down.
Hmm... I've actually tried this but Shift+down unselects the initial selection. However, selecting a single line is still often pretty useful. I'll mess around some more with the keymappings to see if I can work something out.
