I tipped the ME driver a couple of dollars, less than a $1 per bag but not by much. He helped me with the bags in and out of the bus, so that was worth something IMO. I also tip about $1 per bag for valet. If we have groceries I tend to group them together and tip 2-4-1 and a $1 per "real" suitcase. Our valet never leaves with less than $5.
As for the maid, we tip $2-3 per day for 3 of us who keep the place fairly clean. I know it's not a "tipped" position, but we sill tip.