I hear you on the fine hair but there's a lot of good but light leave-ins out there that moisturize but don't weight down. I'd be surprised if you can't find a layering combination that works for you. What leave-ins have you tried?
Silicones can often make your hair "feel" like it's moisturized, but won't actually moisturize the hair. A lot of products that promise exotic oils are actually made up of mostly cones plus a drop of oil... that won't be enough to combat dry hair.