……………………..

You should for sure go to the superday, its a free option for you to meet some people at JPM and see if you like them.  I think the bigger question is should you re-neg if you get the offer.  JPM is obviously the better franchise but that does not mean that you can't have long term success Wells.  A couple of things to consider.    

1. Where did the you like the people better? I know hard to tell from interviews but this is very important for S&T as its very much a people business and working with people you hate will make your life miserable. 

2.  Where do you want to work?  There is a very good chance that with Wells you could end up in Charlotte, if you have a strong location preference that should be a major factor in driving you decision.  You only work 50-60 hours a week in S&T even as an analyst you want to live somewhere you enjoy.  From a career prospective NYC will be a lot better but if you hate NYC you should not make yourself miserable. 

3.  Do you see a lot of Associate and VPs who have started as analysts and worked their way up?  I think this is an underrated thing to look at, as it shows that the firm is committed to developing people internally and not just hiring a bunch of analysts to do the grunt work and letting them go after their analyst stint. 

EDIT: Things I don't think matter all that much   

1. I don't think sales vs trading matters that much, its way too hard to tell which you would like or be good at until you actually spend some time on a trading floor observing and getting a true feel for what its like.   

2. Current analyst pay levels, going to take a couple of bonus cycles to see how total comp shakes out.  Personally I think all the banks will raise base salaries to the same levels for analysts across all front office functions like JPM has done, not sure if that just means bonuses will be smaller but for the time being its too early to determine anything about how one bank is comping its analysts vs another.  Either way you should be more focused on where you can move up the fastest as that is where the real money is.