Quote from MasPanRanger's Guile is actually a good replacement for Vines of Vastwood in my current deck (Monogreen Lash). It still gives the 1 mana instant speed hexproof and is guaranteed to give the +1/+1 without extra mana cost, which is actually pretty helpful when I'm trying to get as many spells out on my Lash'd creature as fast as possible (and generally working with 2-3 mana).
If, on the other hand, you cast the Naturalize in response to the activation of Spellskite, then the Spellskite will have left the battlefield by the time it ability comes to resolve. Since the Spellskite is no longer there, it is an illegal target for Giant Growth, and therefore the ability will be unable to change the Growth's target to Spellskite. It will thus not change target, so when it resovles it will affect the creature you targeted.