How many blocks have no unspent outputs?

[mustyoshi]

Other than the initial blocks with only the coinbase, do any blocks even have the luxury of having all their transactions being spent by now?

[gmaxwell]

I'm sure quite a few do— since there are many with just a couple outputs beyond the coinbase.  But why do you care?

[DeathAndTaxes]

Other than the initial blocks with only the coinbase, do any blocks even have the luxury of having all their transactions being spent by now?

As gmaxwell indicated it doesn't really matter.  You can prune the tx in a block which are spent (it doesn't need to be all or nothing).  Regardless you need to keep the block header to validate the chain integrity.