I don't think you can ever have "too much" RAM or storage space - but your wallet is always going to have a limit. 8GB is my standard PC install, 16GB is my "power user" install....servers I have installed up to 128GB (they use a lot more RAM). Photoshop can use as much RAM as you can throw at it, but if you only use 8GB or 16GB 99% of the time, why do you need the extra memory?