If the voucher covers a flight to Anchorage, AK I'd head there. The weather is still very reasonable that time of year for someone from the lower 48, the majority of the summer tourists and mosquitoes will be gone, and the sun is still up over half the day. There are still a lot of outdoors activities to do, hiking, halibut fishing, scenic drives at that time of year. Not so much the relax by the pool, but there are plenty of cool things to see, Denali being one of them and only about three hours from Anchorage (you can see the mountain from Anchorage on a clear day).
If you thought Colorado was amazing prepare to have that dialed up to 11 in Alaska. Pretty much every large land mammal in America is there and can kill you. It is awesome.