Except for the very serious road warriors who travel 100-300K miles a year and get 100% or more bonuses on flown miles due to status or class of service, anyone with your ambitions is going to have to do it on bonuses. Just because you got turned down by Citi doesn't mean you're out of the game. Premium class travel will never work on cards with pseudo-miles (i.e. points that convert to cash) because you might need 200K points for a $2000-$2500 ticket (discount business class) vs. 100K for real miles.

The USAir card gives 40K miles iwth no spend requirement and an extra 10K each year after that when you pay the $89 annual fee. You can get off-peak Envoy class for 60K less 5K for having the card, so in theory you might be able to get to Europe in business class after two years and $178 in annual fees.

No one here wants to be discouraging. If you can churn cards, it's well within reach. This year my wife and I will (hopefully) each get 55K UA plus about 45K Sapphire preferred, 100K AA, 40K US, and 50-75 Amex, so if you assume we can churn these once every 3 years, we could take an overseas business class trip every year. But that's really the only way to do it.