October in Portugal brings 70-degree days, quiet cobblestone streets in Lisbon, and hotel rates that drop right after peak summer. It is the smartest month to wander through Sintra or sit by the Tagus river with a pastel de nata without fighting summer crowds.
A solid trip for two runs around $4,200 all-in. Instead of draining your savings account at once, you can split that bill into predictable monthly payments while you plan the itinerary.
Keep in mind that 0% interest is a deadline, not free money. If you still have a balance on your Citi Simplicity® Credit Card after 18 months, regular interest kicks in on whatever is left, which gets expensive quickly.