I would spread out the $20k - $30K spend on multiple cards from different banks, to get the mega up front bonuses. Consider 3 American Airlines cards for 50k miles each (yes you can get them all), the previously mentioned Chase Sapphire Preferred card, the INK Bold with Ultimate Rewards card, the U.S. Airways card for 40K miles (first purchase - no spend requirement!), the United Airlines card for a possible 50K miles on first purchase - no spend requirement), the two Delta American Express cards for 35K miles each, and some really good hotel card offers like the ever popular Starwood American Express card, the Priority Club card (Holiday Inn, etc.), the Marriott card, and the Hyatt card.

You can find all of these on my website below in the Credit Cards section.