2 psi plus/minus doesn't make much difference in terms of tire wear.
What matters is to understand the state of tire when you fill them up. If the car has been driven for a while and the roads are hot, you need to fill extra 2 psi to compensate expansion as arkhitect mentioned. 30 psi recommendation on car doors is for tires at ambient temperature that are not run in/hot.
So in most cases tire are hot when you get them filled up so go for 34 psi for civic x and 32 psi for other cars that require 30 psi.
If the tire shop is close to your place and car hasn't been used much which means tires are not hot yet then go for whatever the manual says.
Some people put +2 psi in front tires because most front wheel cars are heavy at the front so the tire needs more pressure to get into proper shape.