First, anyone who does this already has good credit. YMMV depending on your credit scores. Second, two people may separately apply for each individual offer you'll find here on FT. With the AA 75K promos alone, the chances are pretty good any family would get from 300K to 450K miles in AA's program. Two successful Amex Premium Rewards Gold or Platinum applications, made several months ago, would have earned at least 150K Membership Rewards points (and maybe 200K). Delta and Amex ran a promotion that recently ended (and then was reinstated with some modifications) that allowed transfers of MR points to Delta's FF program at a 50% bonus plus sufficient elite qualifying miles to earn Silver status with Delta. United has a credit card that offers a membership to their airport clubs. Many hotel programs, many with 50K point bonuses, offer some level of status as part of their branded cards (and one of the benefits of the Amex Platinum card is Gold status in the Starwood Preferred Guest program).

Third, be prepared for some stiff annual fees in some cases. Many, but not all cards will waive the annual fee for a year or two; others will consider waiving the fee when it comes due if you retain the card; and others will make you pay the fee up front or will do no waivers when the annual fee comes due. You have to decide whether you wish to cancel the card to avoid paying the fee and what the possible effect on your credit might be.

As I noted above, this isn't genius stuff. Just get more familiar with the threads here.