My hair is curly/wavy. It's definitely wavy at the back, but the sides are loose curly, with tighter curls at the very front. This is a source of some irritation to me, as when I was a little Mip, I had 3B hair. Yes, fellow curlies...my hair didn't go curlier at puberty as it did for so many of you...it went straighter and slowly got straighter throughout my teens. It's my fault really - I spent many years hoping and wishing for straight hair.
My hair is definitely a very long way from straight though, whatever I do with it. My main aim is to achieve maximum curliness. I straightened my hair once, and it really didn't suit me.
I completely agree that wavy hair never looks the same two days running. My hair can look sophisticated, or glamourous, or sexy, or cute, or wild or neat (or just awful), but I'm not able to pick the look I want - my hair decides for me.
I am able to do second day though! This is a fairly recent thing for me. If you wake up and your hair looks dodgy, don't automatically soak it with water. Instead, put a shower cap on and have your shower as normal. Then get handfuls of water and damp down your hair and use a bit of gel to scrunch. Any frizzy areas, or areas you want re-shaping - just wet them and put some gel on. I get really good results from doing that, and it makes my hair curlier. It doesn't take long at all, you aren't walking around with wet hair for ages, and you get the 'finished look' straight away. When you soak your hair, in my experience anyway, it can take until my hair is totally dry to see whether it's a disaster or not.
The back of my hair annoys me the most. It's just wavy and no amount of scrunching turns it into curls. The most I can do is aim for fullness and have lots of layers. Good definition also helps.