Last Long Run Before the BIG day!!

So thanks so much for your encouragement and advice everybody--especially to Brent for the last comment- I realized that there are quite a few things I was neglecting to do-- hydrate myself-electrolytes--all that. Oops!
So for my last 20 miler I went with a girl from my ward who ran the Salt Lake City Marathon and she booked it!!! She's one of tiny speedy runner girls...whoa! It really helped push me. I had to walk some of it and she was so patient. It really helped to have a running partner for the first time. I also got some actual running shoes...Mizimos or something and I LOVE them!! I brought gu and those shot blocks... I perfer the gu- and wore non-cotton clothes... yeah, that helped a lot!!
Jann, who I ran with brought a camelback which helped a lot too!! So many things were better about this run. We talked the whole time, got started earlier in the day, and the pace was quick so it really did go by faster. I was glad to hear the advice to walk if you need to. I always feel so guilty for doing it but my body has to sometimes.
I'm wondering that if after awhile my tailbone, hips, knees, and ankles will stop aching if I keep running? I think I'm not stretching enough or something. My muscles are fine- I rarely have sore muscles, but my joints get so achy. I've already noticed it getting a lot better with my arch supports and with taking glucosomine sulfate. I'm so relieved today is over!!! Any advice for the last bit of training or the Big day is really appreciated. Thanks!