Upgrading 5.1 to 7.1

[groovyone]

So, I have a BOSE 5.1 surround sound setup (5 double cubes + sub) with the powered subwoofer. Before anyone gives me grief, I bought them 9 years ago with my Best Buy employee discount when I had a very small living space.

Anyway, I'd like to upgrade to 7.1, but likely cannot get the wife to approve a full overhaul all at once, so I'd like to just add 2 new spearkers, likely in the front L/R positions, (maybe a new center) but still be able to maintain some resemblance of balance with the current Bose in the center (maybe) and remaining surround spots.

Anyone have any good suggections for what speakers I can use to fill the remaining 2 spots that will still be good once I upgrade the remaining 5 + sub? I was thinking about the Bose bookshelf speakers at first, but now would like to go with something more than a stopgap measure. I was more recently eyeing a pair of JBL floorstanding speakers, but am worried they will not play well with my existing speakers.

Any suggestions? (other than tossing the Bose on to the lawn)