We used the same vertical grain fir that we used on our window trim. I found Mr. Plywood to be a great place to buy fir, as they have a nice selection of “shorts” that are about 1/2 the per foot price of custom lengths. Since most of the shorts are 6-8′, they work out perfectly for door and baseboard trim. It’s a (relatively) cheap way to get fir trim. Even though this is VGF while the original woodwork in the rest of our house is flat-grain, it still has a very authentic and original look once it’s stained.