Mexico City in the dry season between January and April is about long walks through Coyoacán, mornings at Casa Luis Barragán, and eating past al pastor lines without melting in a downpour. The weather stays crisp and clear, which makes it the absolute best time of year to spend your days outside exploring neighborhoods.
A typical trip runs around $1800 for flights, a good place to stay, and eating your weight in tacos and mole. Since dropping that much cash at once hurts, you can break it up into smaller chunks over a set window so your bank account doesn't take a massive hit all on Tuesday.
That 0% window is a deadline, not free money, so if you still have a balance left when the 18 months are up, standard interest kicks in on whatever is left.