Triples don't usually have spices added - you get fruityness and spicyness from the Belgian yeast. You can add if you want, it's your beer - but in my opinion, I like to keep the recipe simple to let the yeast complexity shine.
What ingredients are provided in the kit?
If it doesn't come with a real Belgian yeast strain, upgrading to that is the single best thing you can do to improve the kit. Aside from that, I like to do a mini-mash with a couple pounds of base malt along with the extract, so that the base malt enzymes can convert the extract a little more, for more fermentability/less residual sweetness. In my opinion, trying to do high-gravity beers with extract always leaves too much residual sweetness.
Since a triple is a big beer, a long primary (a few weeks), and a long secondary (a few weeks), and plenty of bottle conditioning (a few weeks at least) are good.
Random Fact: Human Immunodeficiency Virus particles have approximately the same density of 1.170 wort. I know because I float them on a sucrose gradient in the lab to purify them for research.
Drinking: Belgian strong golden, Northern Brown, Porter