I did this once - never again...
Arrived totally knackered - excessive taxi fare (because i didnt have the energy to negociate).
Unable to check in to hotel for 6 hours after i arrived - was able to dump luggage but had to cart a heavy laptop bag around.
I ended up sitting in a cafe for the majority of the day as i didnt have the energy to "tour".
But thats just me - perhaps you have little more energy in your blood
Smala01