Here is a listing of shops here in the PNW that work on Rotaries. It's getting harder to find one, so hopefully this list will help people.
Washington:
Jerry's Little Car Shop
www.mazdasonly.com
1517 Central Avenue South Kent, WA 98032
(253) 854-9601
Notes: General service. Works on Miata's, First, Second, and Thirdgen. Has been known to not want to work on modified FD's.
Intek Racing
www.intekracing.com
25911 104th Ave SE Kent, WA 98030
(253) 872-0872
Notes: General service and tuning. Wide range of cars.
Atkins Rotary Specialties
www.atkinsrotary.com
41026 Ski Park Rd E
Eatonville, WA 98328
P: (360) 832-1990
Notes: Rotary engine rebuild parts, porting, balancing, engine parts, rebuilt motors.
Jeff's Automotive
www.mazdamanor.com
13815 Canyon Rd E Puyallup, WA 98373
(253) 537-8075
Notes: General service.
Not shops, but recommended people on various forums:
Jesus Cales-Rodriguez
Fort Lewis, WA
Notes: Engine builder, porting, general mechanic work. Appointment only- you can find him on Facebook.
Oregon:
Portland Area
Pineapple Racing
www.pineappleracing.com
1059 Northwest Corporate Drive
Troutdale, Oregon 97060
(503) 233-3878
Notes: Engine builder, porting, rebuild kits, engine parts.
Track Forged
www.trackforged.com
9324 NE Colfax St Portland, OR 97220
(503) 674-0293
Notes: General service, upgrades, tuning.
VIP Performance
www.vip-performance.com
8216 NE Sacramento St Portland, OR 97220
(503) 257-1110
Notes: General service, upgrades, tuning.
FD3S Engineering
www.fd3sengineering.com
5039410465
Notes: General service, upgrades, parts. Appointment only.
Kurt Robinson
http://www.kurtrobertsonmazda.com/
503-829-6054
Notes: Engine builder, porting, chassis/engine parts. Old school parts.
With any shop, research and referrals are your best way to prevent being ripped off. Do your research, call around, and make up your own mind who you want working on your car.