It's a long walk.. but not 20 blocks... 10-12 or so (south of chicago on lasalle) (chicago being 800n - monroe being 100s - state being 0 and lasalle being 200 or 300w - gotta love the chicago grid)
+1 on Elephant and Castle although I would rate most of the food there as average..
I'd also add Russian Tea Room.. It's a nice rather authentic (or so I always believed) place.. Do some shots of Vodka with your waiter
Berghoff is always a classic.. Even if it really isn't what it used to be.. Was better when the old man ran it.
Harry Careys is really good.. Prime rib sandwich at lunch is awesome.
That Cajun place on State and Kinzie... Red something.. ugh name escapes me.. Red Fish I think
Ditkas (best damn burger around... and every once in a while Mike will stop by to chat.. and you know what? I'm not really a celeb guy.. Normally couldn't give a shit.. but when Mike Ditka walks over.. asks how everything is going.. and pulls up a chair to chat for a few with your group.. that's pretty fuckin cool
and lets not forget Gibson/Hugos
Grotto on state
Ginos East (go to the one on Superior in Streeterville)
There are some good italian places on N state.. 500-600N are (south of Ontario.. on W side of St.. Authentic Italian names.. Tratoria Stato or something to that effect
Sorry if the list is getting a bit long.. Just a few places of varying quality I like in that area...
Come on over to the Grocery store next to my office.. They have a decent little cafe and 200$ a lb ham that Mort says rocks
(i'm to cheap to find out... I'd rather go by a camera or something than a lb of ham)