i cook for a living and therefore am pretty picky with my food. these following spots will not disappoint. trust me. here's my 2 cents
ANH HONG(vietnamese, geary and leavenworth). try their 7 courses of beef
ANA MANDARA (vietnamese, ghiradelli square). shameless plug because i used to cook there lol. try the claypot fish
fish n chips: CAMELOT (manor in pacifica) is THE best
dim sum: KOI PALACE (serramonte). shanghai dumplings ftw
pasta: CAFE SPORT (columbus and green in north beach). it gets no better, 4-cheese seafood pasta and scampi are both a must. plus they give you free dippinthat's crack
NAMU (asian fusion, balboa between 4th and 5th). kitchen closes at 1am, resident dj spins nothing but hip hop. best loco moco i've ever had. ever. rare tofind a high end spot open this late
TOMMY'S JOINT (van ness and geary) for your hof-brau foods. and 100's of kinds of beer.
MARCO POLO (taravel around 25th ave) for gelato. many exotic flavors you cant find elsewhere, such as soursop, durian, guava, etc.
NIPPON SUSHI (skyline and manor in dc/pacifica) for cheap sushi. place is kinda grimy but it's a bargain.
GOLDEN DOOR (?) BAKERY (grant between pacific and broadway) for egg custard tarts. 2x as expensive as other bakeries, but 2x as good
STACKS (burlingame) for your breakfast needs.
SUSHI ROCK (polk or grant) or KOBE SAKE (crystal springs and el camino real) usually has very good quality sushi. any spot that has toro regularly is good inmy book.
RUTH CHRIS' (van ness) for steaks. usda prime, son. nuff said.
ZUNI CAFE (hayes valley), best roasted chicken in sf for years running. it's hyped up for a reason.
i'll add more later...