The recessed bases supplied with the Wrath of Kings require a different approach to the flat topped bases more usually supplied with miniatures from other ranges.
I have seen bases that use the standard techniques within the recess and look good doing it. I've also seen ones which go for a more scenic look (the models painted up for the Wrath of Kings studio army are a good example of this). I have chosen to take the middle ground.
I had hoped to be able to find some way to incorporate counters onto the base, but I could not devise a way to make them both useful and aesthetically pleasing without going way way too overboard with engineering. So simple bases it is.
I've used fairly basic materials to make my bases. The main bulk is built up using bits of torn up cork mat. I sourced mine by buying cheap cork table mats from Amazon, and taking a pair of needle nosed pliers to it to rip it apart. PVA glue was then used liberally to affix it to the base (see below for why this is important). Once that was dry I added a mix of sand, flock and slate chips to add texture to the base and fill any offending gaps, again using PVA. I've used bigger bits of slate where they look good. Once all that has set solid I've just poked two holes in the right place for the pegs on the model's feet and superglued it in place.
I quite like the finished effect, as it gives the base a character and depth that is not achievable when using other bases without adding ridiculous height to the model.
A side effect of the silky finish to the bases is that the PVA glue does not form a solid bond. This means that once the base is set in place I can pull a magic trick and separate basing material from base...
While not an ideal thing to have happen during a game, this means I can give the models a spray undercoat without worrying about needing to come back and repaint the edges of the base, ruining their finish. If I wasn't worried that the serendipitous cork base would fall apart from use I'd be tempted to find a way of making them at 30, 40 and 50mm and doing away with the plastic bases all together.