A classic ganache uses equal weights of couverture or semi-sweet chocolate and cream for a light filling, 2 weights chocolate to 1 cream for truffle, or 3 chocolate to 1 cream for glaze. Sometimes, as Blueicus implied, a little butter is added to the cream. Vanilla, liqueur or booze are typical additions -- to make it taste good.
The "foolproof" (but not the classic) method of making ganache is to chop the chocolate into small pieces, bring the cream to the boil, add the butter, stir to melt it, then remove the cream and butter from the heat. Beat the chocolate into the cream, preferably with a French whisk (heavy wire, elongated pear shape -- made to incorporate ingredients rather than air) with fast strokes, relying on residual heat to melt the chocolate. Blueicus mentioned adding butter "to the end," but I'm not familiar with that, I learned to put it in the cream before the chocolate.
In the classic method, the chocolate is melted before adding the cream to it. Done right -- better gloss and texture. Done wrong -- lumpy disaster.
Assuming your technique was similar to one of those described, what ratio of chocolate to cream did you use? And, what do you mean by "rich?"
Ghirardelli is excellent chocolate with a distinctive taste. It's barely possible that your sensation that the ganache was extra rich came from Ghirardelli's unique quality, but not likely since it's in so many other product lines -- e.g., Starbucks (ugh!) uses it quite a bit -- so you're almost certainly familiar with it. Starbucks aside, it's hard to do better than Ghirardelli, only different (and more expensive).