Upper Eastside recommendations
Good breakfast at Yura & Co on 92nd and 3rd.
Uptown on 88th and 3rd for a good burger and after work drink specials.
Cafe D'Alsace for good, basic French... excellent Choucroute Garni and well known for their beer list.
Agreeing with other posters about Wu Liang Ye, Brother Jimmy's (fried pickles!) and Cavatappo Wine Bar.
No Indian spots come to mind worth mentioning
A 23 year old looking for fun should really look elsewhere, but I know Lenox Room on 3rd between 74th and 75th is a mainstay of the preppy UES set that also has decent, if somewhat pricey, food. J.G. Melon, which is across the street, is justly famous for its burgers and has a more laid-back bar scene.
Surprisingly enough, Shanghai Pavilion, at 3rd between 77th and 78th, has some of the best soup dumplings in the city.
Bardolino / Caffe Buon Gusto - good, decent, hearty Italian
Doc Watsons - cute dive bar
Wu Liang Ye - "authentic" Chinese food
First Wok - "American" Chinese food
TASTE (in Eli's) - good place for a glass of wine
Simla - good Indian takeout
Yorkville Diner - BEST diner food
Umi - amazing sushi rolls
Googie's - hearty outdoorsy brunch
La Tour - all you can eat mussels / french fries
Cavatappo Wine Bar (2nd Ave between 89th and 90th). Great, small, wine bar with good tapas and an extensive wine list. Their sister restaurant, Luca, (1st Ave between 88th and 89th) is good too. Both are relatively inexpensive.
Ryan's Daughter (85th and 1st) is a good Irish bar and they have free bags of chips.
Eli's has good brunch
I'll second Beyoglu. Great for small dishes.
I also like Ottomanelli's Cafe on 1st btwn 85th and 86th. It's friendly, inexpensive and has very good food. BYOB too!
Gino's on 83rd btwn 1st and 2nd (closer to 1st) has a pretty good slice, though the best in the 'hood is at MiMi's at Lex and 84th.
Finnegan's Wake on 1st and 73rd is a good pub when you're craving comfy bar food. So is Fiona's on 1st and 87th.
To hang out and have coffee, a beer or a fattening dessert, there's DTUT on 2nd and 85th. Free wifi.
And speaking of fattening, my favorite black-and-white cookie in the city is at Glaser's Bake Shop on 1st and 87th. Only $1.50 too!
Don't know about "fun" places, but for breakfast there's Googies on 78th/2nd, for Indian there's just Baluchi's on 82nd/2nd, Dakshin on 1st/88th (good but spicy) and Mumtaz on 83rd/3rd (good). Penang on 83rd/2nd is inexpensive and good, and if he likes Turkish there's Beyoglu on 81st/3rd. There are tons of places around, he'll have to explore!
Googies is wonderful, and great french fries.
Also, Brother Jimmy's around 76th and 2nd Ave. for Southern food - especially deep fried okra with spicy pork gravy:
(There's another location up in the 90s.
)Near the Brother Jimmy's - maybe a block or two south - is a place to get burritos the size of your head that is pretty good. And there's a fancy deli on a northwest corner in the upper 70s that's fab for snacks.
That is, in the late 90s these places were there.