Welcome to FT! Just a quick point: although you can stack a lot of miles over the next 6-7 years, keep in mind that airlines tend to readjust their programs every so often, and generally more frequently than every 7 years. As a result, goals you might think you've reached may suddenly become out of reach again because of a devaluation of a FF program.
In regards to cards, you're probably in good shape since you haven't touched the big three of Citi, Chase, and Amex. You can get AA cards through Citi, UA and BA cards through Chase, and Delta cards through Amex. A credit card for US is available through Barclay's. Look to the MilesBuzz and Credit Card forums here at FT for more information on these cards.
Another set of cards are good because of the flexibiity they offer. The Amex Premier Rewards Gold Card and the Chase Sapphire Preferred earn points in their own proprietary programs that can then be transferred to a number of airline and hotel partners (UA/BA/Hyatt, amongst others, with the Chase card; BA/Delta/Choice, amongst others, with the Amex cards that participate in their Membership Rewards program). One more card in this genre is the Amex Starwood card which primarily earns points with the Starwood hotel group (Sheraton, Westin, W Hotels, and others) but also has a very favorable 1:1 transfer ratio to a number of airlines--with a bonus of 25% for transfers made in blocks of 20K SPG points. MilesBuzz and the Credit Card forums can keep you up to date with the best offers for these cards as well.
In addition to the SPG Amex, there are many credit cards that offer hotel loyalty points that can be worthwhile, especially if you and your husband can open individual accounts to double up on your earnings (of course, the same principle applies to airline FF programs). After all, once you've flown somewhere, you'll need to stay somewhere. It's worth some time to review the individual hotel forums here at FT for the programs you're interested in to learn about their strengths and weaknesses.
As I mentioned, time can work against you to some extent given the changes that any of these programs may make over the time frame you're looking at. On the other hand, you have plenty of time to prepare and gather miles/points. I'd use the time to get acquainted with the various programs and credit card options (you'll be amazed how many credit card offers discussed on FT are much better than the offers you'll receive in the mail or see on TV ads). You'll get a better feel for which airline programs will work for you best out of PDX as well. No reason to jump into applying for cards when you can take a little time to do research to find the mix of airlines/credit cards that will help you get where you want to go.
If you get really serious about collecting miles/points, reading FT will become a regular hobby, but I guarantee you, it's well worth it. I started here just a little less than two years ago with the goal of lining up enough miles to do an airline trip to Scotland in first class in 2014. I blew past that goal over a year ago, and now find many different ways to earn miles/points that I wouldn't have considered several years ago.