For something that isn't even a recognized BJCP style, Session IPA really does get around! This time of year, I'm always looking for good beers to take to the beach, and I don't know that anything fits the bill better than a good Session IPA.
Light in body, bright in flavor, and surprisingly approachable (for something with "IPA" in its name), it's a darned-near ideal warm weather, happy-hour-through-dinner easy-drinking beer. Brewing a keg of this to have on hand throughout the summer will be a good investment of your brewing time, and they're actually a bit more complicated to make than we might assume!
This isn't just a question of reducing the gravity (although that's one way to go, and we will be): it's a question of generating a lot of flavor from hops and finding light ways to balance those flavors. Otherwise, you're really just brewing an American Pale Ale. Let's crank up the AC and get to work, shall we?