720 is darned good. When a lender considers you for a mortgage or other loan, they'll usually go by the middle score, but don't be surprised if they use the lowest one to determine rate, so if they're all close you're okay.
One thing I learned is that if you do have multiple credit cards, they do look for you to pay them ALL off on a steady basis--this big chunks on one, etc., doesn't help as much. Also, "opt-out" if ever given the chance, because inquiries, whether you wanted them or not, will hurt your FICO score. What I've found helps is that if you charge something significant then pay it off and do that a couple of times over several years, it helps your score immensely. AMEX is nice, but not as beneficial as you pay that each month. Also, too many credit cards, even with zero balance, will hurt because it shows potential to get in over your head.
Finally, when I was buying my current home, my FICO scores were in the range where I was basically able to knock 1/4 point off the rate simply because of my credit history. If you can do that, then YOU'RE in the driver's seat, even in this time of tight money.