Richard Florida has posted a nice map (originally from National Geographic) showing which cities have the greatest numerical disparity between single men and single women. It appears that I'm in a pickle, being a single guy in L.A., which has the largest excess of men over women.
But wait a minute... the spots on the map are based on absolute differences, not scaled for population. It looks like Las Vegas has about 20,000 more single men than women, a difference that constitutes about 1% of the Las Vegas region's population. The L.A. region has a larger difference of 40,000, but that constitutes only 0.3% of the region's population. (It would be even better to take the ratio of men to women in each region, but I don't have that data.)
Also, shouldn't we take demographics into account? I'll bet a lot of those single women are aging widows. Notice that the retirement mecca of Miami has a rather large female-over-male disparity. (I'm reminded of this old post about where to find single women.)