You know, it seems like ALL transfers have SOME fee or two. Some are obvious, others are buried in the transactions.

Institutions just don't usually transfer at the interbank rate.

I've found that ALL of my hundreds of international ATM withdrawls were at interbank +1% (or sometimes more, depending on the home bank's greed), even though no "ATM fee" was ever added.

Perhaps the only way to do a totally fee free conversion would be to exchange currencies directly with another person at that day's interbank rate. This would seem unlikely to happen.

OP: there will be many expenses while living in the Netherlands. There may be minimal surplus to convert if you relocate to the USA some years later.

Besides, who would move back after living in the Netherlands?