I've come across a wide range of IPLs. Some are just AIPAs with lager yeast. Others are closer to an APA with lager yeast. I've seen a lot that are more like a strong pale lager with moderate bitterness and a big hop flavor/aroma but a softer flavor than a lot of IPAs.
I'm most a fan of this latter set of beers which I find is best accomplished by blending fruity American hops with continental European hops. I like putting cascade and aurora together as a base and then adding hops to round out the hop profile. Cascade/Aurora/Aramis is a really nice combination. (Incidentally I take a very similar approach to saisons.)
But if you clarify what you want in your IPL I'm sure we can supply more specific recipe suggestions.