  Open clusters potentially provide an ideal environment for the search for
transiting extrasolar planets since they feature a relatively large number of
stars of the same known age and metallicity at the same distance. With this
motivation, over a dozen open clusters are now being monitored by four
different groups. We review the motivations and challenges for open cluster
transit surveys for short-period giant planets. Our photometric monitoring
survey (EXPLORE/OC) of Galactic southern open clusters was designed with the
goals of maximizing the chance of finding and characterizing planets, and of
providing for a statistically valuable astrophysical result in the case of no
detections. We use the EXPLORE/OC data from two open clusters NGC 2660 and NGC
6208 to illustrate some of the largely unrecognized issues facing open cluster
surveys including severe contamination by Galactic field stars ($>$ 80%) and
relatively low number of cluster members for which high precision photometry
can be obtained. We discuss how a careful selection of open cluster targets
under a wide range of criteria such as cluster richness, observability,
distance, and age can meet the challenges, maximizing chances to detect planet
transits. In addition, we present the EXPLORE/OC observing strategy to optimize
planet detection which includes high-cadence observing and continuously
observing individual clusters rather than alternating between targets.
