I think that part of it depends on the situation. While 4 & 5 do seem excessive, if you are planning on returning to the hotel many times in the near future, then it might be considered an investment in the future (especially if the hotels do not belong to a loyalty program). I generally only tip the concierge if it is a hard to get reservation or something very unique. If I know where and when I want to go, and all that person does is pick up the phone, I see little need to tip someone $20 to do their job.
My question to the OP is do you tip some of these people at the beginning of your stay or at the end?