I certainly don't have extensive experience with concierge, but we did stay 1 night at PP this year, and they did not leave rice crispie treats. They did on our first ever visit, when we were also celebrating my twins' 5th birthdays. That trip and last summer at PP we got the chocolates and turn down service (not staying concierge) and both DLH and PP left "cards" and towel wrapped birthday cake when we stayed. Look on the hotel threads, there are some very good pictures that show you what the offerings are. They do a decent continental breakfast every morning, including espresso and good coffee (way beter than the room coffee) and soft drinks. The offering get a bit nicer going up from PP to DLH to GC...but I was totally happy with what even PP had. In the evening they do wine/beer reception and hot items and a lovely variety of cheeses (I love cheese) and then desserts goodies. You can still get free movie rentals too (didn't use them).
When I think it's definitely not worth it: when it's not for a family of 4 or more and you're on a budget, when you won't be in the room much at all (otherwise you might only be able to take advantage of breakfast time). If you are splurging and will be in the hotel often enough to take advantage of more than just one breakfast, etc or pampering the family then it can be "worth it". Also keep your eyes open for discounts, sometimes the concierge rooms will also qualify for a 25% off room-rate discount.