What day would you choose?
I can honestly say that I can't come up with a single day I'd want to revisit. Not sure what that says about me exactly ...
I might be more interested in an opportunity for a "do over" where I could re-start from a particular point in my life with the full benefit of the knowledge and wisdom I've gained over the years. More from curiosity about how things would play out differently than any great expectations that THIS time I wouldn't screw ANYTHING up and no one else would either, resulting in a life of unmitigated wonderfulness.
I thought that was what it was going to be in the beginning - an alternate life as afterlife. I have a couple of days I would like to change however I would miss what I have.