A blend that is mostly Perennial Ryegrass is the lawn of chaoce in the Northwest. It is normally blended with smaller anouts of fescue. I noticed tht there are now "Nortwest Blends" for sale.

here is a good cheap example:

Here is a link that might be useful: northwest supreme

this one has a bit more going on:

Here is a link that might be useful: pdx mix

Most local retail garden centers will have lawn seed blends suitable for a variety of PNW growing conditions. They will be various combinations of fescues and perennial ryegrasses. The fescues tend to be much more shade tolerant than the ryes, so look for a blend that features them. These are often labeled as directly as "shady lawn mix" :-)

Ryegrass requires more sun to thrive but tends to hold up better to foot traffic. Fescues also tend to be more drought tolerant than the ryes, another reason blends featuring these seeds thrive in shadier areas under high tree canopies.

I used one of the "eco lawns" in a previous home. I really liked the clover for it's year round green colour and nitrogen fixing attributes. However, I did not like the yarrow - it just doesnt blend. It seemed to grow bigger and faster than grass and clover and looked unsightly ( insert eye of beholder caveat)

I am installing a lawn and will likely overseed with white clover which you can buy seperately from a lawn mix.

yarrow seems to work well if mow height is very high. looks good in athletic fields with english daisy, clover, etc.