changing measure/BarLine spacing defaults

[Kieren Richard MacMillan]

[ Lilypond 2.8.1 ]

Hello, all!

I'd like to put a little extra padding around every BarLine -- i.e.,  
I find that Lilypond puts the first note too close to the beginning  
of the measure and the last note too close to the end.

Unfortunately, I can't seem to find the right combination of space- 
alist values -- can anyone give me a hint? Or is BarLine.space-alist  
not the thing I should be messing with?

Thanks,
Kieren.