My cat is what I call a "mipper". If you speak to her, she'll reply with, "mip". She also finds the hallway in the middle of the night that has the best echo and meows there indicating that she's finished sleeping and so should the rest of the house too. She's more of a talker and whiner than a yowler.
There is a cat at our barn that you can hear meowing before he's in sight. He just meows and meows on and on. There's nothing wrong with him either, he just is very vocal and his meows are so long and drawn out. I would imagine he is a lot like your cat.
I read somewhere that cats have over a hundred vocalizations. I don't know if it's true or not but it makes sense given their personalities! ha ha