I've got huge windows on my house. The commercial cleaners just don't work - like you said the streaks start appearing in a day or two. I've found this recipe very effective:
1 cup rubbing alcohol
1 cup water
1 tablespoon vinegar
1 teaspoon ammonia
Using isopropyl alcohol and white vinegar together makes a quickly evaporating spray glass and mirror cleaner that eliminates streaks. The vinegar adds a mild acid and the ammonia a general cleaner and grease cutter. Use lint-free towels (I scab all the left over coffee filters at work).
-- John