I also logged in to my United MileagePlus, and noticed the United Airline 50,000 Bonus Miles. Add an authorized user will net another 5000 miles. I did not apply United MileagePlus credit in the past and have been accumulating United MileagePlus points in various affordable and natural ways, such as United MileagePlus Dining and Earn UA miles via United partners' flights. I shared my experience earning United miles via Eva Air in my Eva post. (Note: United 1K member can earn 2x United points whenever flying United. In that case, flying with United partners' flights (such as Eva Air) to earn United miles is not a good deal).
Chase Sapphire Preferred Ultimate reward miles would catch United attention next time. Approval for Chase Sapphire Preferred requires excellent credit score. I believe that there are always exception. That is why I opened a checking account with Chase bank for myself, and another one for Isa. Each of our accounts received a $125 to $150 bonus also. We intend to keep these checking accounts.