To reach good views, you typically will face a strenuous uphill hike. If you are up for the challenge, I would recommend Chataqua or Mount Sanitas.

I believe that Mount Sanitas only has like 2 or 3 trails so it is fairly obvious where to go to get good views (take the uphill hike behind the rocks) and you can see all of Boulder. Chataqua has a TON of trails so I would visit the visitors bureau before taking a hike and ask the ranger where a good place would be to get the best views.