This is one of the lovliest walks in the world. Not only is there natural beauty along the way, but there are sculptural elements remaining as well, where humans have clearly been.
I would recommend walking in during the cooler morning hours. It is roughly 1.5 miles. Enjoy the Treasury, etc. Then, if you choose, ride back through. The appropriate tip is $5. They will ask for more in a demanding fashion. It is a cultural thing. Stick to the five dollars...and do not give them a dime of it until the end of the ride, unless you want to find your backbone jammed into your brain. Time is money afterall. If you have already paid them, they are going to rid themselves of you as quickly as possible to find a new customer. You can, of course, give them more if you think they have given you exceptional service.
If you walk back through in the afternoon, after your time exploring, stick to the shade every moment you can. Don't hesitate to sit down if you find an accommodating spot.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC