"Whichever airline you choose, get the credit card that helps you earn miles on it. UA has a Chase Visa, AA has the Citi Mastercard and NWA has a US Bank WorldPerks Visa. To get the best SIGN ON PROMO, dont just go by what you see in a seatback flyer or the company web site, rather, visit THIS thread and it will also help you with lots of cool travel and flight tips!"

Sign on promos are nice, but you might want to consider a cash back card if you can. Some of them will give you 3% back on your top 3 categories of purchases. Lets say you spend 3k/month on hotels, restaurants and flights, you'll get $1100 cash back over the run of a year. It sounds like you'll have plenty of points for flights, so that will give you flight+spending money. Add in the Marriott points and you'll have a nice vacation at least once per year more or less free.