I must be one of those nice, super-polite people too...although I think I'm just behaving as my mother taught me. I've been comped meals or given vouchers for free meals, been upgraded on flights and given freebies in shops.
Just last night my DH, 13 month old DD and I were at the pharmacy. Apparently they'd had a huge amount of screaming, squealing kids in that afternoon (it's school holidays in Australia). We were lined up at the counter and indicated to the cashier that a 6 year old was actually ahead of us in the line and then we organised my DHs prescription and waited for it. Our DD smiled and waved at everyone, giggled when people gave her attention and blew a kiss to one of the cashiers who was dealing with a grumpy customer. They actually gave her a teddy bear (and a gorgeous, cuddly one at that!) with the comment that she'd made their day. I was so proud, especially when she said "Ta" as they gave her the bear and then she gave it a cuddle and said "Ahhhh" before waving goodbye to them.