Last long run before NYC

Well, I will blame it on my 5k race yesterday, I wouldn't call the run bad, but it wasn't good either. Definitely not like the 1st 20 miler 3 weeks ago. Out at 6am, mid 60's but with a good breeze and clouds. Tried to do what I am planning for the marathon. Clothes - can only do some much as I don't know what the temps will be. Did have a little chafing with my shorts (which I have Never had before) but that can be remedied. Tried over the last few weeks to like the Power Bar energy gels, but will end up carrying my own Gu. 2 in my water bottle clip have a tendency to come out, 3 work great. But as I will be going thru them - I won't always have 3! Decided to take water at each stop immediately before/during/after the Gu, but feel ok doing the Gatorade at the others. I drink alot running or not, so I will take something at each stop. If it is goig to be over 65 or so - maybe even 60 - I may carry a clip with a water bottle. I am still not sure about a disposable camera. Tried velcro on the side of my shorts. Wasn't too bad, but was coming off after a few miles. Need something else if I am to take that along. I will walk at each water stop for no more than 30 seconds. I know that amounts to 13 minutes, but I will be moving and I do think it will help in the long term. I am more concerned about feeling ok afterwards than I am with time (assuming I break 4:18!).
So I did 20 miles, with a couple of hills at the beginning and ~ mile 15 (NYC bridges!). Again a steady 8 min/lap pace. Looking at my lap splits - I went out too fast. It's too dark to see my times for the 1st hour at least. Was under 7:50 each lap the first 6 laps and ended up doing 2o miles (or so) in 2:58. So about the exact same as 3 weeks ago. However - the last half lap - behind my right knee started getting sore. Not bad, but I could see it affecting my running if I had gone longer. Luckily - I can coast for the next 3 weeks!