I considered poker chips before I considered doing Casascius Coins... my problem was that I couldn't strike a good balance between price, quality, and function (I wanted them to have real BTC value).  But I have never done chips before so I was starting with an average hand.  If you can do well... by all means.

One big drawback is once the novelty has worn off, they will be equivalent to regular poker chips that simply have a decorative bitcoin symbol on them, because that's what they are.  What denominates a chip is what the house says it is, so the printed BTC will serve no functional purpose.