I don’t like using the Capital One travel portal, because it adds a third party between you and the airline/hotel. I will use it to book a night or two or rent a car just to get the $300 credit.
Where do you want to go? I would start with that question, and also look at their transfer partners. I haven’t done that, but they have a number of European airlines, as well as Air Canada and Aeromexico if you’re looking for an international destination.
I tend to use my Capital One rewards to cover travel that doesn’t have a rewards program. E.g., independent hotels or VRBO/AirBnB.