Is it best to visit NYC on Mon-Thur or Thur-Sun in August? I'm traveling with a toddler, so it would be especially nice to avoid the long lines at the musuem/tourist attractions and busy subway commute during the day. It would be cool to check outdoor events that the city has to offer. What are the disadvantages and advantages for weekdays vs. weekends?

Weekdays will get less tourist traffic but more commuters so if you avoid the typical commuter time, you will have less congestion. Weekends would be more fun if you are interested in people watching.

In August many locals will be away on weekend but there will be more visitors. So it depends on what the lines are for.

If you're talking major tourist attractions weekdays are your best bet - but you should buy advance tickets whenever possible - for as early in the day as you can get since by late afternoon you will be frying with all the heat reflected back off the pavements. (In fact, with a toddler I would be either back at the AC hotel or playing in the park by later afternoon.)

August is typically a slower time in NYC in general when you don't find long lines at museums. With the strong British pound, that may be changing though. Early August may be busier than late Aug. for that reason.

Outdoor events tend to happen more on weekends, but places like the Statue of Liberty will be busier on a weekend than a weekday.

The weather will be hot, but the city isn't very busy (relatively speaking) on weekends in August, when a lot of people are on vacation (more people are on vacation early than late in the month).

Hotel rates are cheaper on the weekend. Attractions (particularly those that attract families) are busier, but tourist attractions in NYC are always busy, so I'm not sure it will make all that much difference.

It will be very very hot.

If you eat in the residential areas there will be smaller crowds on the weekends.

August can be brutal with the heat and humidity. And even though some subway stations are somwhat better many are still like decending into hell. Ironicallly the extra heat comes from the A/C units on the trains.