Affordable? SF? Same sentence

On 3rd Street you have Chevy's and CA Pizza Kitchen. Both chains, but within your budget.

SF is not really a diner town. The closest to you is a Mel's on Mission near 4th, but I can't recommend it.

As for bakeries and cafes, you'll find some good ones in North Beach on Columbus or nearby, but that's a bit of a hike from your hotel.

As for Thai, one of my favorites is Little Thai at the corner of Broadway and Polk. Also a fun area to walk. About a $10 taxi, or you can take the 45 union bus to Polk for $1.50 each.