Things you can do other than try to build such a large military are: Research diplomacy techs. Get the Universal Translator Trade treaties. Well, at least try to get them, you can only give out one of each. Give gifts every so often. And as was mentioned: Trade routes and getting them to fight each other. Still, without the military it will be difficult to keep everyone liking you. But with these ideas maybe it'll just be one at a time declauring war on you.