While holding a few ETH for the long run is a good and safe idea unless you've got a ton of money I wouldn't gamble everything in it expecting massive returns as the time to get in this one was under $50.
Keep some ETH buy Litecoin XMR,XRP,ANS,Iconomi and hold.
I agree diversification is best, and your choice of coins to hold is mostly good but for the love of god don't touch XRP that is the biggest fail of a currency based on nothing but fake hype.