First, buy the BWI-MDW ticket - don't burn an award on that. You can get that one cheap on WN.

Second, pick two programs and forget about the rest. In your case, looks like WN and US. If I had a million miles on US, I might be panicked about their financial state; at low levels, I wouldn't worry about it. It doesn't sound like you need to "bank" hundreds of thousands of miles for many years with US. Hit your award level; grab a free transcon on UA or US and have fun!

Third, hook in your primary credit card to Dividend Miles Dining.

Finally, your credit card. I have to admit, I've gone round-robin through many different program cards to pick up sign-up bonuses. Held the UA card for a couple months to get 20,000 miles, held NW for a year to get another 20k, still have the AA card to try and milk a renewal bonus, and I have all the hotel cards. If this game interests you and you have the time/energy to manage a lot of active credit, staying on top of the various payment dates and bonus terms, keeping an eye on your credit score, etc. - then go for it. You can earn a LOT of miles and points as your fill your wallet with credit cards.

But...if that game doesn't interest you, just get the SPG Amex. In the near-term, you'll diversify your award possibilities by earning free hotel-nights very quickly. And before you know it you will be so awash in Starpoints that you can transfer out to your FF programs (including US) if you need an award. You actually get MORE bang-for-your-buck with this card than you do a traditional mileage card. Lower annual fee than an airline card, plus a 25% mileage bonus when you convert in chunks of 20k.