Pizzerias in Rome are like Tex-Mex joints in Houston -- they're ubiquitous, they have basically the same menu, and, on average, they serve a pretty tasty meal. In Rome, there are basically two types of pizza -- pizza rustica, which is a chewy/crunchy crust with a myriad of possible toppings. It's baked in giant rectangular slabs that are cut into square pieces, sold by the gram, wrapped in wax paper, and served to-go for easy munching while you take part in the evening passeggiata.
The other type of pizza is served in sit-down joints and is usually a forno a legna pizza -- that is, a pizza baked in a wood-fired oven. It's a thin, crispy crust inspired by the famous pizzas of Naples. These places use a set menu with the standard pizzas being napoletana, margherita, bianca, prosciutto e funghi, etc. It's one pizza per person, served whole, and eaten with knife and fork.
In Houston, the closest approximation to this type of pizza is served at Dolce Vita on Westheimer. It's one of the only pizza places in Houston (that I know of) that uses a real forno a legna. Grimaldi's and Russo's use a coal-fired oven -- a decidedly American invention. I have not seen any coal-fired ovens in Rome.
Over the last week, I've had several very good pizzas in Rome proper. Then, during an excursion outside of Rome to the ancient Roman port town of Ostia Antica, I was surprised to find one of the best pizzas I've had in Italy. There's not much to Ostia Antica -- a train station, the ruins of the ancient town, and a touristy-looking pizza joint. History tells us that the port of Ostia Antica is where the Greek hero Aeneas landed on his way to helping found the city of Rome. So this pizza joint had campy Greek decorations -- even the waiters wore togas.
But the restaurant also had an impressive forno a legna. Two pizzaioli stood by, efficiently assembling and baking the pizzas. I had a pizza margherita; a dining companion ordered a calzone. Both arrived piping hot with superb char on the crust, which had a delicious, salty flavor of fleur de sel. My pizza was light on the sauce and heavy on the cheese. The mozzarella was laid on thickly and bubbling when it arrived. The sauce added a faint sweetness to the overall experience. Although this joint didn't look like much, it served up the most memorable pizza of my visit to Italy.