ultimately it's a difference of opinion. i'm not going to sit here and tell you that your experiences with speaking in tongues are invalid. to me the Bible is pretty clear about it, but from personal experience...i've seen weirder things. i do have some ideas about it (including why when ppl do it, they see results) but it's totally outside the scope of this conversation.
it's just not something i personally subscribe to. belief in tongues isn't a make-or-break kinda deal anyway.