You can apply for a regular travel rewards credit card that will allow you to earn miles on all your purchases and redeem them with Sun Country or other airlines. Most of the travel rewards cards are Visa Signature cards or World Elite MasterCard credit cards. Both types of cards give access to similar benefits and privileges. Travel cards will allow you to earn miles on all your purchases, not only on airline tickets or in-flight purchases, which is common for airline co-branded credit cards. Earned miles can be redeemed with any airline of your choice.