artstuff makes some good suggestions...you can visit more than 1 of these towns in a day too. You might want to consider purchasing a Retour ticket between Amsterdam and Rotterdam, that way you can get on and off as many times as you want and stop at many of the towns listed above. I think the average time at each town is about 2 hours but of course your experience may be different.

I am middle-of-the-road in the love or hate Amsterdam: I definitely liked Leidseplein, Vondelpark, the Jordaan and various canal districts MUCH better than Central around the Dam, Red Light District, etc. (it was quite gray, dim, crowded, and dirty to my eye).

I toured only on foot, solo, female for 5 days my first time in the city last summer. I did not witness crime or drug dealing.