So what are the differences between the geometrid and the noctuid? Obviously, the hindwings would have been a hint and unfortunately, I only have 2 shots of that one and in both, it's wings are tightly shut. I don't remember it having bright hind wings (in fact, while I was trying to ID it in bugguide, I skipped any that showed that). For future, is there a distinguishing feature I can look for to tell them apart (and is the colored hindwings a feature of the noctuids?)? I can already tell that I'm going to have to buy a book and start studying the different types of moths. I think they're beautiful, but don't know the first thing about them.

One obvious difference between noctuids and geometrids is the way they hold their wings. There's a very useful article here that shows the differences in silhouette between the major moth groups (The noctuids are there under the name "Owlet Moths").

As for the colorful underwings, that's characteristic of only one part of the huge noctuid group (They used to be classified as a single family, the Noctuidae, but now they're a superfamily made up of several families). The underwing moths often look very much alike- until you see the patterns on the underwing. That's why a view of the underwings would have helped.

In case you're wondering: Tony's the real expert. I just have a bit more time to explain things.

That link you included will come in VERY handy! I wish I'd had it months ago, heehee, because I'm really bad at ID'ing moths. I will definitely consult this guide first before searching and posting more images. Again, thank you.

Bright hindwings or not, these markings seem like a dead ringer for a Catocala species of some sort. Perhaps piatrix or cerogama....but I've been wrong before.