Portugal is better when the summer crowds go home. In late October or early November, the Algarve is quiet and the light is gold. You can walk the beaches without fighting for space and eat at the best spots without a reservation. It is still warm enough for a light jacket, and the air is crisp.
We usually see this trip cost around $4,200 for two people. You can handle that cost by spreading it out. If you use the Citi Simplicity® Credit Card (Citi), you get 0% for 18 months on purchases and balance transfers from date of account opening. That means you pay $233.33 a month to cover the trip.
The interest-free period is a fixed window, not free money. If you have any balance left after the 18 months, the card's regular interest rate will hit the remaining amount. Stick to the monthly schedule to avoid that cost.