I have been to Beijing three times in the past 5 years, for 5-6 days each time. We only walked or took taxis, so it was 2-4 taxi rides a day. We thought taxis were very cheap. We were horribly stuck in traffic only once, going from the train station to the hotel (Park Hyatt). This was in September, which we were told is the worst month traffic-wise. The other times were in Easter, I didn't think traffic was that bad.

Taxis could be a bit difficult to find though, not because there weren't any but because the drivers didn't want to go in our direction or their working day was ending. We always managed to get where we wanted to go but sometimes we had to wait for 15-20 minutes, especially when leaving the hotels to go out for dinner.