One Sim Card for Netherlands and Belgium
 

We will be starting our travels in Amsterdam and ending in Brussels. Is there one sim card that can be used in both countrie. Is it possible to purchase it in Amsterdam easily? I would be using it for reservations and local calls. I live in NYC and would use my number if my son or daughter needed to contact me but most times I would just use wifi.

Since both countries are in the EU they are subject to the price restraints for roaming that are imposed by the EU. SO whilst you will be roaming with it in Belgium it will not cost you a fortune to do so (assuming you are talking only phone, not data).

You can buy a PAYG Sim at any telecoms shop - the Phonehouse, Vodafone shop, etc and even at an Albert Heijn, where you can buy a Sim card for €9,95 and get I believe it is €15 in calls with it.
You will need to make sure you have enough money on it for Belgium, before you leave the Netherlands, if you choose the Albert Heijn card, since you cannot reload it abraod without a Dutch bank account. You can buy extra time at any Albert Heijn supermarket though. If you buy €10 worth you get another €10 free, though those bonus minutes are limited to a month, whereas the rest are valid for 9 months.

According to the Dutch Albert Heijn AH.nl website you pay 10, 20 or 30 euros and get a bonus of resp. 10, 30(!) or 60 (!!) euros...

The bonus cannot be used for calls to or in other countries.
To get the bonus you first have to call 1244 and give the bonuscardnumber.

Calling the US would cost 0,75 euro/minute
Calling in NL costs 0,35 euro/minute (deducted from your at least doubled credit)
Receiving calls from abroad costs 0,13 euros/minute.

Re the Albert Heijn bonus on prepaid phone cards: you will need a physical 'bonuscard' in order to get the bonus amount. It's sort of a membership card so don't forget to ask one at any AH supermarket in the Netherlands (or in Belgium) before you buy the phone card!
Although IMO the AH prepaid card isn't the best option because you won't be able to make use of your bonus outside the Netherlands.

Rick Steves recommends GWK Currency exchange at Central Station.Is this a good place?