where is the best place to begin a walk through Chinatown then Little Italy (ending up at Katz's deli).

I'll be coming from the WTC site.

Head toward Mott or Mulberry Street in Chinatown. When you get to Canal Street keep walking on Mott or Mulberry and you'll cross over into Little Italy. You'll know when you see the many cafes and restaurants. When you reach the Houston Street, walk on East Houston. Cross Allen Street and stay on East Houston until you get to Ludlow Street. Katz's is right there. Explore the Lower East Side after Katz's. It's a very hot trendy neighborhood.

A very good book is Access New York. It's got maps and shows block by block where the interesting places are.

I don't get Little Italy/Chinatown; I guess I'm not doing it right, and I'll try Flynn's suggestion next time I'm there. I've had two mediocre meals, dealt with swarms and swarms of people, looked into shops of no interest.

Peg,
Don't knock yourself out trying to get Chinatown/Little Italy. There are much better areas close by that you will get.
It's not like you can't get good Chinese and Italian elsewhere if that's what you're looking for.

For those interested in visiting the area coming from WTC but not interested in eating, Flynn has outlined a great itinerary that will cover both sections without having you tread much on Canal which is an overcrowded zoo of street vendors and lacking in real shops.

If interested in eating, I suggest meals at Wo-Hop at 17 Mott (downstairs)or snacks at <a href=http://www.ferraracafe.com/>Ferrara's</a> (where many of the Italian restaurants on Mulberry get their desserts) on Grand. But since you are heading for Katz, I am sure you will want to save your appetite for the big meal.

I personally find Mott & Mulberry a photographer's dream because of the scenery and personalities. Unfortunately, there is not much left to see of Little Italy other than restaurants. Chinatown, however, is still a lively center of activity with many grocery stores and decent restaurants interspersed with the souvenir sellers.