For pale ales, 1oz per 5g. That will get you SNPA level hoppiness. Double that if you likes the hops aroma.
For IPA, sky's the limit. Just make sure to dry hop after the fermentation is finished. Don't want the CO2 to scrub the aroma from the beer.
Sorta OT: SMASH pale ales and IPAs are a little bleh. For me, you just have to have some crystal malt in there (for interesting backbone to the hops) and a # of wheat (to maintain a nice head and lacing). At least the crystal, though.