I find that delivering my own in the evening is better and on occasion, I get called back in the street to give a quote there and then! The best result was when I delivered about 150 leaflets and I managed to book 3 jobs in. So take your diary too
Paying someone to deliver them is a gamble in my experience. I advertise in a local rag and I found a load of them dumped the other day :

I did have a friends kids delivering for me and they were telling me people were approaching them to ask how much for a living room carpet to be cleaned etc etc... Of course the boys just requested they rang me.... Which they never did

Also, as you suggest yourself, if your leaflets amongst other leaflets they tend to get filed straight into the bin....