Kauai in late April and May hits the sweet spot. Spring break crowds have cleared out, summer travel hasn't started yet, and the trails on the North Shore are drying up nicely. It is the best time to hike the ridges and relax on calm beaches without fighting for parking.
A typical trip runs about $4500 for flights, a rental car, and a place near the water. If you pay with the Discover it® Cash Back, you get a 0% intro APR for 15 months on purchases and balance transfers. That lets you break the trip into payments of $300.00 per month so you can clear the balance without paying interest.
Keep in mind that a 0% intro window is a deadline, not free money. If you still have a balance on your Discover it® Cash Back when the 15 months end, regular interest rates kick in on whatever amount is left.