Hey Neo.......Youz be in the right place I believe....Um......your problem....Is it that you feel that the lyrics are too prosaic for the music or something? Do want help or are you looking for a lyricist? I'm not quite sure what your asking.....when you say "are there people who write great lyrics but lousy tunes?" you are talking about the opposite of what you feel your problem is right?I get the feeling that you think the lyrics are too mundane and prosaic and don't quite express emotion that is tantamount to the quality of the song...
Anyway........What I would try to do is take each line of your song and isolate it.......Maybe put each line on the top of separate piece of paper and underline it........Now, look at the lines isolated and think about them separately..and be honest with yourself.....What exactly was it that compelled you to write each line? Could you elaborate on each line alone and add more detail and colorful language to each line as a stand alone concept? Think of it like you are writing a bunch of new songs; each one based on each single line......Jot your ideas down underneath the underlined lines on each page.......You should find that this method should generate enough inspiration and language to base your song on.........When your done with elaborating on each single line read through the pages and see what you like.....Now, base the lyrics of your song on that stuff.....Anything you don't use for this song you can put on the "shelf" for a later song....I guarantee you will have many new and interesting ideas....
I admit, that this is a much more systematic and conceptual approach to song writing......Most people prefer a more emotional approach...one that "goes with the flow." However, I assure you that this method will generate "flow." It is just away to organize and refine your ideas and shouldn't be viewed as a "box" that ties you down....I find it wierd that most people tend to think that using a "conceptual" framework such as this for producing art presents some sort of obstacle en-route to a creative/emotional self expression...Infact, I find that the opposite is usually true......Anyhow, this is how I look at alot of my work.....I learned to use this method with my art work and it has carried over into my musical endevours.....I start simply and go from there; elaborating on the simple ideas until they reflect the complexity of emotion and content that I feel is warranted.....People are very complex by nature and not to acknowledge your own complexity is to sell your self short; inevitablely winding up with a contrived, unauthentic, unaccurate self expression......"self expression" is what art is about...right?
Anyhow, you could think of it as an outline for a paper....Infact you could even write an outline instead using the separate pieces of paper......Each line could correspond to a roman numeral, it's details corresponding to letters..etc etc etc......
Just something to think about...maybe you could give it a try....Ofcourse I haven't heard any of the music nor do I know exactly what you are asking but this is my reply
........If you post the tunes I'll listen.......In most cases, It is hard to judge any lyrical content w/o the song.... ....However, If you try the method I suggested you should wind up generating enough material; at least enough so that some of it will inevitably wind up fitting into the prosody of the song by mere chance alone....
Good luck