I get both sorts: an early morning commute (6am) through the centre of town (Kensington High St, Picaddilly, Clerkenwell Road) which has very little traffic usually, but yes, a few idiots who think they can get away with driving badly that early. The morning commute normally takes aroun 40mins.
Coming home at 6pm is much slower and I reckon much worse: loads of traffic, pedestrians wearning iPods or on phones who step out without looking, red-ligh-jumping cyclists/motorists and plenty of buzzy scooters and loud motorbikes. Normally it takes me just under an hour although I do go right along the Euston Road from Kings X to Paddington. I did manage two brief bursts of 25mph last night, but that's the exception rather than the rule.
Best/worst of both worlds! My usual weekend training route is on some fast A roads and if I haven't been out for a while the first 60mph pass does send the nerves a-jangling.
EC