Portugal is best in the shoulder season. Late September or early October means the Atlantic is still warm, the crowds in Lagos are gone, and the seafood prices drop. You get the limestone cliffs and the tile-covered streets of Lisbon without the summer sweat or the peak prices.
A trip for two usually runs around $2,800. Instead of dropping that all at once, we can use the Discover it® Cash Back to spread it out. It has a 0% intro APR for 15 months on purchases and balance transfers, so you aren't paying extra to wait.
The 0% rate is a tool, not a gift. If you still have a balance after those 15 months, the standard interest rate kicks in and gets expensive fast. Pay it off before the clock runs out.