Not sure what you deem 'classic'? But if was me, I'd ditch the 20 and 15 minute additions for sure. Heck, I don't add 10 minute either to ipa's. My late additions go in at 5 and flameout and whirlpool. Then dry hop with 1-2 oz. YMMV.

*your hop choice should give you a nice citrus/pine brew.

 

You're definitely on the right track. O's suggestion of more Crystal is on the mark. I might even add a couple ounces of Honey Malt.

Simplifying the hop additions is a good thing, but I personally like the complexity and depth of flavor that can be gained with some smaller addition at the 20 minute mark. I brewed a Cascade SMASH that had over a half dozen additions and it was fantastic.

As for Dry hop (and, yes, you should), Cascade or Centennial will do quite well. I'd have a look at Willamette, as well, if you're interested in old-school NW style hop profile. The spice/floral of Willamette makes all the citrus of the Cascade really pop.

Other "classic" hop combos that I've used for NW style IPAs include Chinook/Centennial, Columbus/Centennial, Nugget/Cascade/Willamette. When I want to get some dank character, I like Simcoe because it carries pine and fruit that seems to balance with just about anything.

 

I think of "classic" NW hops as the varieties that were developed in the 60s, 70s and 80s that were used by the "first wave" of American craft breweries like Sierra Nevada and Anchor. Willamette, Cascade, Chinook, Nugget and a number of others were in heavy rotation Those are the piney, citrus-y, floral, earthy flavors that I associate with NW style beers. A lot of new hops started being developed specifically for the booming craft industry in the 90s and continues with new hops that are big on lush, dank, tropical flavors along with lower levels of the citrus or piney bite that's more familiar. I like those flavors, especially Simcoe, but I personally find that moderating the juicy quality by combining with crisper flavors from the older varieties.

 

I get ya on the classic now. Admittedly, I do miss some of the older style IPA's with the real firm bitter bite like Sierra in the past years. I'm still a big SN fan. I do like some of the newer styles with high hops and low ibu's, but I still love me some tongue curling bitter brews too.

 

It's not the bitter that I like and in fact I prefer IPAs with a smoother hop profile, but the flavors of the old-school hops are really nice. A perfect example is Bell's Two-Hearted. Decent level of bitterness without that harsh, lingering sensation and with big classic hop flavor...all Centennial.
And another beer that I discovered that's become my absolute favorite is a traditional IPA from a brewery in Tacoma. Big malt without being sweet and huge hops without being harsh - something like .070 gravity and 70 IBUs - so the beer is balanced in a way that makes the hops absolutely prominent without letting the bitterness get in the way. That beer is Columbus, Magnum and Willamette.
Finding the perfect hop profile and bitterness level in an IPA was a big factor in me digging deeper and deeper into homebrewing.