Maggie, Like you we use different airlines. The card that has worked well for us to accumulate f.f. miles is the American Express Starwood card. The points can be transferred to virtually any airline. For every 20,000 points transferred, they add 5,000 points so you actually get 25,000 miles!! We just let the points pile up until we decided which airline to transfer them too. The only airline that isn't part of that (as far as I know) is Southwest. http://www.starwood.com/preferredguest/partners/all_partners.html?back=-1

or you can apply here:
https://www66.americanexpress.com/c...fined/0/n&from=2&mgmID=undefined

There is no membership fee for the first year, after that it's $30 per year. I use this card for EVERYTHING. Although we have the AmEx Platinum which cost $395. year (use this only to get shipboard credit), I actually use the Starwood card to pay for Radisson cruises and everyone else in the world! So far it's worked the best for us.