I decided to go with full grassed bases, and on figures that have more space on their bases, I'll add additional stuff like rocks, rubble, etc. Recently I've started basing my figures so that the sides of the bases are flocked as well as the tops, so that they blend in much more with the terrain - though like all bases, the effect is best when the tabletop is the same type of terrain as the sides of the figure bases. Here's the Dalek Commander with grass flocking, and a wall from one of the cardstock ruins kits I mentioned in an earlier post.
The grass mat is a Citedal Battle Mat, available from places like Games Workshop. The flocking I use is the grass flocking from Flames of War, and I find that while slightly different in tone (more so in real life than when looking at it in photos), it still matches the Citedal Battle Mat very well.