I guess in the situation that you mention, it may be better to circle. If the road is not wide enough for a half-decent driver to get by your pulled-over car, you should keep moving. Otherwise, sitting beats circling for a number of reasons:
1) It is just as likely that someone will pull out right where you are sitting as it is that someone will pull out near the random spot you are at while circling. And…
2) If you are sitting, then you have chosen the most convenient location to park
3) Sitting is less stressful than driving around in circles, especially when you have to face red lights, double parked cars, stop and go, etc.
4) It uses less gas, so you waste less (both from a yiddishe gelt perspective and an environmental one)
5) There is a better chance that someone will notice that you want a spot and inform you of one opening up.