Thanks to everyone who contributed recipes in the thread below. I ended up going with pastrytroll's chocolate cake (seems ultra-American-traditional and also easy). I used curiousbaker's buttercream and also krissywats's custard buttercream (for piped decorations, because I ran out of the swiss buttercream due to the need to use a lot for the sides to make them appear uniform).
The cake is good and the recipient was quite happy with it. It has a weird shape because I made three layers, two in standard 8" cake pans and one in a spring form one, and that, though also labeled as 8", turned out to have a far smaller diameter and also domed like hell... so it ended up being shaped a bit like a sand cake a kid would make with their toy pail. But I kind of like it.
Anyhoo, thanks all!!! I'll be sure to try all the other recipes over time.