We tipped her 20%. She unpacked the groceries, and even made a second trip with a bottle of bubbly that we decided on after we'd already sent her our order. She said she would be back at OKW again that day and wouldn't mind dropping it at the front desk, for no extra delivery charge. I thought that was really nice of her.
The one thing that I wish I'd done differently was to be much more specific in my list. I was specific to brand and size on certain things, but told her on everything else to get the smallest/cheapest size available. Some things I KNOW couldn't be the smallest ... like the 32 oz bottle of salad dressing? and we asked for a 6 pack of Pepsi (thinking cans) and she brought a six of 1 litre bottles. I was trying to keep the grocery bill under $100 to avoid the bump up in delivery charge, and it ended up being over by about $10 -- Hmmm. And we weren't allowed to keep the grocery receipt. She said she'd make a copy of it and leave it at front desk, but she didn't. I thought that was kind of weird. We'd do it again, but be super specific on the list.