I've been plugging away at improving the roads in Vancouver Washington. First, I'm surprised at how big that area is. Second, I find a lot of the TIGER data is "off by one" or shifted/compressed compared to the aerial imagery.
I've found the combination of NAIP imagery and JOSM works quite well for this. JOSM lets me select several point for moving which is way more efficient than Potlatch. The detailed Yahoo! imagery is the best, but it's old and the level of detail drops off a lot outside the big cities.