Utah's red rock country is worth the hype, but timing is everything if you want to actually enjoy it. Go in spring or fall when the temperature drops out of the triple digits and you can hike Zion, Bryce, and Arches without melting. You get cooler air, smaller crowds, and way better light for photos.
A solid trip usually runs about $1600 once you factor in gas, park passes, a rental car, and a mix of camping and hotels. Spreading that out over time takes the sting out of booking flights and car rentals all at once.
That 0% window is a deadline, not free money, and any leftover balance when the 18 months are up will get hit with the regular interest rate.