I thought you might be interested in the darts in my t-shirts. This pattern piece started out as Kwik Sew 2565. The changes are the side bust dart, the french dart, and the neckline. The original neckline was a crew neck with a thick band. It fit great, but it was not the best look for me. I have large breasts and a short neck, so a scooped neck or v-neck would be better. I decided to work on the scooped neck. The first attempt was okay, but I thought a deeper scoop would be better and the opening was too wide. I'd changed the band to a narrow band. So on this version, I brought the neckline in at the shoulders (& upper back).
As for the darts, the t-shirt is undarted with a bit of easing at the bust. I don't like to use easing because on me, it's more like gathers, and that basically a big wad of fabric under my arm which is at a height that is already big enough around, thank you. The first bust dart worked very well in terms of fit and final appearance, so why did I want to change it? Well, it's a friggin' big dart, and I hadn't considered that I could just cut away the interior of the dart when cutting, so it made the pattern piece very wide. I also thought a french dart would be more attractive, providing me with the shaping I want at the bust, but removing some of the fullness under the bust. I still have my waist. Rotating the side bust dart to a french dart worked well for fit and appearance, but it had the same problem that the side bust dart did. It's a frigging big dart, making the pattern piece very wide. So I decided to do a little of both in this version.