Why fly when you can apparate?

[allies426]

No: HPFGUIDX 175517

I suppose this was just for the sake of the plot, but several times 
when Harry is somewhere that Voldemort is rushing to get, Harry 
pictures him flying over landscapes.  

Flying?  Why fly?

Apparition is much, much faster!  Even for arguments' sake if he 
couldn't appareate INTO the house, he knew exactly where Nagini was, 
why not apparate outside the house and *then* fly?

For that matter - do we know that Vodemort CAN appareate?  The Death 
Eaters apprate to him when he presses the Dark Mark, but have we ever 
seen the reverse?

Allie