When post-processing I sense there is a certain pressure to focus on a particular width v height ratio on the final image. My advice is, where possible, to treat the photo on its merits and if you are printing/framing it, make the frame fit the photo rather than the other way around.

That said, I am finding very wide (panoramic) is appealing to me more and more for landscapes; I've even printed recently into a large frame 3 panoramic images one above another which I'm delighted with. I also tend to like the 5x4 ratio (more portrait layout than landscape).. I'm not sure why - it just seems to work, and I have this in mind when I am framing the photo.

Where this can breakdown unfortunately is portraits, especially when you are asked for a photo for framing. Let's say you've taken a family portrait and you have cropped it nicely to print onto 6x4" (photo snaps in old money). A relative then wants to print it for 7x5"... you should be okay if there is enough space around the edges, so hopefully no cropping. However, when you are then asked for an image to frame in a 10x8" frame with a 0.5" border all the way around all hell breaks loose - you can't crop it as it will ruin the image... the only trick really is to always take the photo with enough space around the sides so that you can crop to your relatives' desire.