You might research Speedwell (Veronica 'Whitewater'). I'm unsure if it's a sterile hybrid, but I like the way it's behaved so far. It's just entering its second season here, however, so it's a bit early yet for any definitive conclusions. I do like the fact that it's one of the earliest groundcovers here to spring back into action -just as soon as the snow is gone.
More info would definitely help:
Height
Use
Full sun/part-sun/bright shade/shade
Windy/protected
Dry/moist/wet
Semi-evergreen or deciduous
Will watering during dry spells be difficult?
Anything that you can add will help to narrow down the options.
