I think I would break down American IPA into 3 categories: West Coast IPA, New England IPA and "Other Places" IPA (also known as "cheap on the hops" IPA or "Sorta Strong American Pale Ale").
For West Coast IPA, I think any pale base malt works: British Pale Malt, US 2-row, US "Pale Ale" malt, or even pilsner malt. I know a lot of brewers who like to cut their 2-row with a little pilsner malt. Still, some like to cut it the other way, with a 50/50 2-row/Maris Otter mix.
As for specialty malts, Carapils and Crystal are common additions, though neither is strictly necessary. The more old school you get, the more crystal/caramel flavor there will be. Victory/biscuit is also a common addition, or maybe even melanoidin or aromatic or honey malt (in small amounts). I like lighter or medium crystal malts anywhere from 2-8%. Sometmes a little wheat malt is added and sometimes a little Munich or Vienna malt is added.
For hops, the BJCP guidelines will give you a decent idea on IBUs. I think the most common hop schedules are probably 60-15-0-dry or something like that. Lots of people have moved to FWH-whirlpool-dry or incorporated more complicated schedules. AFAIK, dry-hopping became standard practice in IPA sometime during the W administration. 2-4 varieties of aroma hops are common. For bittering, many will use a clean neutral bittering hop like magnum, but others prefer a rougher hop like CTZ or Chinook -- it depends on taste. C-hops are classic, but plenty of people use fruitier new hops. I think the combo of Simcoe-Amarillo is considered "classic" at this point, though neither is a "C-hop." Expect to use around 10g-30g per gallon of flameout/whirlpool hops and 5-30g per gallon of dry hops.
Standard Old School West Coast IPA Recipe:
12 lbs US 2-row
1 lb C-60
8 oz Carapils
Mashed at 152F
1.065 OG, 60 IBUs
1 oz CTZ 60 mins
1 oz Cascade 15 minutes
1 oz cascade, .5 oz centennial, .5 oz chinook flameout
1 oz cascade, .5 oz centennial, .5 oz chinook dry
WLP001 (though any American yeast or most English yeasts will work)
Not so old school:
8.5 lbs US 2-row
4 lbs US Pilsner malt
8 oz CaraHell
8 oz Carapils
OG ~1.064, 60 IBUs
Mash at 149F
.5 oz Apollo 60 mins
2 oz Amarillo at flameout, then slowly cooled for 30 minutes to 140F
2 oz Amarillo, 1 oz Simcoe, .5 oz Citra Whirlpool 140F for 30 minute "hop stand"
2 oz Amarillo, 1 oz Simcoe, .5 oz CTZ, .5 oz Citra dry
Imperial Joystick or WY1450 (though any American yeast or most English yeasts can work)
I really like the difference between Breakside IPA and Breakside Wanderlust IPA -- they are both great west coast IPAs, but the former is more traditional and the latter is a little more modern.