Trying to decide between 8/10-8/17 or maybe the end of September. Have gone in Oct, Nov, Dec and Jan before and wanted to go when the parks are open later. Are parks open later in Sept? Worried about it being too crowded in August not to mention too hot! A couple of my friends always go the last week of August and love it that time of the year - they say it is not crowded and a great time to go - is the second week of August the same??