I find that smart UV project is usefull for AO bakes while modelling, but once the model is set you want to make your UVs manually before texturing. I tend to choose "project from view" for mostly plain surfaces, "unwrap" for more curvy ones and "follow active quads" for some specific cases like weapons barrels. It improves the workflow while texturing, but no automated mapping can understand this. Also, I scale UV island according to their importance (detailed parts get upscaled, poorly visible or plain parts get downscaled. Finally, cramping your UV islands manually let's you get bigger UVs which in turns means more details. And lately I've been putting debris textures into the main texture, which means I have to reserve the space up beforehand.
So, I don't think there's an alternative to the manual process, except for some very simple models.