Wow. You aim high in specs haha.
32GB will be more than enough as for right now but RAM is soooo cheap then why not, right?!?
More RAM the better, always. But 32GB is already such a great amount let alone 64GB so either way you'll be good. I work with large commercial projects on 12GB and I do just fine on the latest build of Revit MEP 2012. It's about time for me to start hounding I.T. but for the most part - still doing great.
Hope this helps.