Today I struggled a bit with pylab's plot_date function and overlapping date tick labels:

overlapping plot_date xticks

After some googling, I found that matplotlib offers nice flexible date tick control and formatting. I added a date tick locator and a date formatter to the mix as follows:

import pylab
import matplotlib
import matplotlib.dates

fig = pylab.figure()
ax = fig.gca()

# Plotting stuff here ...
ax.plot_date(dates, values, 'b.-')

# Set major x ticks on Mondays.
    matplotlib.dates.DateFormatter('%a %d\n%b %Y')

and now I have this plot:

nicely formatted date ticks