Like I said in the unique names that I plan to name my kid (whenever I have them) Adalyn and the last name will be Lee. I love how Adalyn Lee sounds. If you wanted to keep the Lee part you could do Leann or something a bit more feminine.
I plan to go with Adalyn Mae just in case the kid doesn't want a "slightly" unique name.
I've always loved how Adalyn Grace sounds though. It just depends on how the last name sounds with it.
You could always do what we ended up doing and nix a middle name altogether. After two months of coaxing me into giving our son his middle name, my boyfriend decided, while we were filling out the birth certificate paperwork, that he didn't like his middle name and it didn't sound good with our son's name (which it didn't). Rather than attempt to solve the middle name dilema in the hospital we just decided to do no middle name altogether, since really you can always change it later.
Adalyn Grace does sound good, but my boyfriend and I aren't agreeing on names, haha. I do like the way Adalyn Rose sounds too. There is a possibility that we nix the middle name, because Adalyn is such a strong name.