Not to pile on, but OP's question is a bit like someone asking how to lose weight without doing exercise or significantly changing one's diet.

OP--I think you need to downscale your desires to fit the reality--it is far from modest to travel overseas in premium classes several times a year using a discover card. At this point you probably would be best sticking with one airline/alliance until your credit profile increases. I'd suggest American if you can talk them into giving you the card or (in 3 months or so to distance yourself from the citi inquiry) apply for a United card and start building that relationship with chase. As you suggested, put all your spending on that card. Read more on this board and in general about other creative ways of meeting/increasing spending. At this point your goal should be 1 or 2 international economy trips in the next 1 to 2 years. When you have increased your credit profile in 2-3 years and can start churning with the best, the sky is the limit.