I'm new to SF and have a 2 mile bike ride to Caltrain every morning and a 3 mile bike ride home. The morning ride is flat / downhill and through the city. The night ride back is mostly flat (taking the Embarcadero north) and then hilly at the end (would be fine just walking it up at that point since it's steep but short).
I was hoping to keep the budget around $700 or less, but could be convinced of the merits of going a little beyond that if necessary.
I don't know a ton about bikes, but am hoping to have this bike for a long time. I'd love some recommendations on a specific bike or type of bike that I should look at purchasing.