Yosemite in late spring is hard to beat, with roaring waterfalls fed by melting snow and clear views of the massive granite peaks. You will want to reserve your entry pass months in advance to actually get inside the park when the weather turns and the trails dry out.
Big trips like this add up fast, with lodging, gas, and gear all hitting your bank account at once. Spreading out those costs helps keep your cash flow steady instead of draining your checking account in one weekend.
That 0% intro APR is a deadline, not free money, so make sure the $1200 balance is fully paid off before the 15 months run out or you will get hit with interest on what is left.