Thinking about the written language

I have often been annoyed with written English. The fact that two different words can have the same spelling but different pronunciations and meanings is just stupid (ie lead a horse to water and lead sinker). I have been going back and forth on what a proper written language should be like.

One idea is that every possible sound in the language should have a symbol. This was originally the purpose of the alphabet, but new sounds have been included and some have changed. The only way to make this system work is to have a reference that shows the symbol and produces the sound. That would work but with our current technology it requires an electronic recording to make the sound, which wouldn't be ideal for teaching others the language in a non-technology environment.

Another direction is to use symbols that represent whole words. The problem with this is that you end up with a lot of symbols and there would be no way to represent new words (like a new name). It would in some ways be easier to learn, but in others would be totally impractical.

So what would make the ideal written language? Something that is unambiguous and simple to learn. Something that is somewhat flexible so that new words could be added, yet firm enough that you the pronunciation and meaning of a written word wouldn't change over time or vary by geographic area. Any thoughts?