Travel Tip, Please

So, exciting news this time is that Kevin has an interview in Hampton, Virginia. We're hoping to make it a family trip because I have never been out there and it is a perfect excuse to see Auntie Jenni. The question this time is related to travelling with a nearly 2 year old. Of those of you who have travelled with little tykes, what works better for long flights, through the night or daytime flights? It will be AT LEAST 7 hours on a plane with at least 1 plane change. Do I gamble that she will sleep some if we are late at night, or am I asking for trouble. I hadn't even considered the night option (leave here around 10 pm and get there around 8 am) but there are some cheap flights and...well, let me know what you think. I haven't ever flown with a kid for more than a couple of hours. Help! :o)