Why not have both
Yes. This is the correct answer to all of your decision questions from this point forward.
If you're talking about the La Cotte Simple pattern, the hemline length is to taste. There's no set measurement on it, so you can make it as long or as short as you want it.
I don't know how much sewing experience you have, but if you are unsure about making it, I personally would recommend making a mockup out of a cheap fabric like muslin before cutting up your more expensive material. Then you can see if you need to add/remove material, or modify the pattern. You can always cut away excess material if you have too much, but it's a bit more difficult to add material if you don't have enough.