I need the most drought tolerant Bugle there is...anyone have a suggestion? I am try to decide between Bugle and Yellow Moss Sedum for a full-sun slope. All suggestions appreciated!
In my experience, Ajuga really isn't very drought tolerant at all, and it would be a lot happier in less sun than you're describing. I think you'd be a lot happier with the results if you use the Sedum. Sedum acre is the one you're talking about, isn't it--it has a lot of different common names. Sedum acre is a succulent, so it's drought tolerant right from the day you plant it, though it will spread faster if you water it regularly in the beginning. However..... It can become invasive! It spreads on the surface, so if you keep it under control from the very beginning, you'll probably be ok. But..... Any little pieces that fall off will root where ever they land! So watch out for that too!
You could also consider your regular California purple ice plant--I don't know the botanical name, but I'm sure you know what I mean! And another possibility is Mexican Evening Primrose, Oenothera berlandieri 'Siskiyou'. This one is invasive too, and it spreads underground so it's harder to control, if that's going to be a problem for you, but they bloom for a long time and are real pretty.