My son has been declined twice when applying for the Chase SW card. My understanding is they require a pretty solid credit score and income to be accepted.
If you wait until the fall, SW offers major points bonuses for applying for their card. Don't settle for the 40K, wait for the 60-80K range. If you are a business owner, you can apply for their business card on top of a Plus or Premier card, stack your points and get Companion Pass super quickly. We have "gamed" the points bonuses by applying every 2 years for a new card and have had Companion Pass the entire time our Mid has been at the Academy. We haven't paid for airfare to DTA (or anywhere else) in over 3 years. For Commissioning, our family of 3 will travel to Annapolis for $33.60 (+points) total, roundtrip. Also always check SW hotel offerings. Often times chain hotels on their site offer major bonus points to be added to your account.
I second what
@Heatherg21 said on calling to make last minute flight changes as well. SW is extremely accommodating to military. We've even had them just change our Mids flight at the same rate we paid initially, no upcharge in fare. Also, it helps if as soon as you set up a Rapid Rewards account for your Mid, or add it if they already have RR, call SW and include their DOD # under their account to ensure they get TSA Pre Check on their flights. You can also list this under Secure Traveler Information, Known Traveler # when booking.