Late autumn and early spring are the best times to see Amsterdam without fighting the summer crowds. The canals are quiet, the museums are actually manageable, and you can duck into a dark brown café when the weather turns brisk. It is a slower, better version of the city.
A typical week-long trip from the US runs about $2800 for flights, lodging, and daily spending. Spreading that cost out makes it easier to swallow, but you need a plan so you do not end up scrambling when the bills come due.
That 18-month window is a hard deadline, not free money. If you still have a balance left on the Citi Simplicity® Credit Card when the intro period ends, standard interest rates will kick in on whatever you owe.