Running with Groups

I have the opportunity next Saturday to do my final long run, 21 miles, with a “group” from a local running club. The cost is minimal and you run the first 21 miles of the actual marathon route. Part of me really wants to do it, and part of me does not. Help me out and let me know what you think:

Pros:

1. Four water/fuel stops. I was dying of thirst after my 20 miles on Saturday.
2. Accountability running with others.
3. Get to experience nearly the entire marathon route before the actual day (know what to expect).
4. Teammates are doing it – opportunity to meet them before Marathon Monday (or ever).

Cons:

1. I hate running in groups.
2. I want to experience the marathon route the DAY OF and take in the entire experience (be surprised).
3. It’s pretty early and need to figure out logistical transportation getting to Hopkinton.

Thoughts?

Days until the Boston Marathon: 41 (crappppp!)