Discoloured tooth what are the options

My big front tooth is going a light brown colour. The discolouration seems to be working its way up from the bottom and has now got half way (by the way I dont smoke). My dentist has suggested using a lightening product which requires wearing a gumshield with the bleach in it at night. I am not sure about this as I do not want to lighten the rest of my top teeth as they are fine. I feel the bleaching will need redoing ever so often. I want something which will last years.
I suppose I could have it crowned but the tooth itself is fine its just going dingy and is now looking odd compared to the others. Is there a coating the dentist could put on which would permanently bright it up. I dont want a veneer, but I thought I read about a composite coating. Has anyone had anything like this done?. My dentist seems to be in favour of the bleaching but I am not keen as it seems an ongoing expense.