What grass to overseed Pennington Ultimate Grass Lawn?
I live in a suburb of Seattle/Tacoma WA, approx 4700 s.f. lawn, a mix of full sun and partial shade. I seeded the lawn about 6 years ago with Pennington Ultimate Grass Seed (only sold by Walmart) after rototilling in a 5-way soil mix. It appears the seed I used is discontinued. I have some areas I need to fill in as large as 2' x 1' and general overseeding to thicken the lawn (the large open areas were due to moss invasion which I removed).
I haven't been a lawn nut and am trying to learn about how to care for lawns. I've increasingly become very aggressive on removing moss. This is the first year I raked in Cedar Grove Compost into the lawn which is recommended by Ciscoe Morris, a local gardening guru on TV, on an annual basis. I have been fertilizing the lawn each Nov. which I've been told is the most important time and sometimes early summer when I get around to it, I use organic lawn fertilizer such as Dr. Earth. I also annually apply Super Sweet lime to the lawn which is also recommended by Ciscoe Morris since our soil is generally aciditic here if left alone.
So I'm open to anything re: what type of grass to fill in and overseed with but obviously need something that is going to be compatible color-wise with what I have and also hopefully a similar growth rate to what I have. I like the look of upright grass much more than the look of spreading grass. I have just started reading about Perennial Rye, KBG, etc. so I'm very new but am open to opinions.