There are several things one may do all in one day. It is probably best to begin in Meidun-e Emam a.k.a. Meidun-e Naqshe Jahan (Picture of the World Square) around which you will find the following:
-Masjed-e Emam
-Kakh-e Ali Ghapu
-Masjed-e Sheikh Lotfollah
Interwoven into this complex is a wonderful bazaar where one will walk past the various sections dedicated to carpet sellers, gold and silversmiths, jewelers, and just about anything else you might imagine finding in a bazaar.
Other things you might look for are Iranian pistachio candy, the best of which is made in Esfahan. It is delicious and is worth picking up few packages to bring home.
Esfahan is one of the best places to do your shopping. There one may buy beautiful block print textiles, carpets, laquer boxes, silver trays and much more.
Quick Tips:
Though Esfahanis have a reputation within and among Iranians as being some of the stingiest and most miserly human beings on the planet, I cannot say that I witnessed that aspect of Esfahan and its people. As in all parts of Iran, one frequently needs to or should haggle when buying something. You need not worry about offending anyone by suggesting a lower price.
Best Way To Get Around:
Taxis remain the best way to get around but since Esfahan is a nice city with broad boulevards it would be worthwhile to walk around a bit and discover various parts of the city on foot.