FWIW, I think if you can retire before 65, you should do it.
Life is too short unless you are one of the fortunate few that really, really love your job. I'm good at my job, but I don't love it.
So comes down to when you can reasonably retire. 2 big factors (1) how much you have saved and probably more important (2) how much you will spend.
Rough formula
1) Total Savings
2) x 4% (using rule of 4% as "safe withdrawal rate")
3) - healthcare expenses
4) - est. Fed taxes (maybe 10%)
5) - est. State taxes (maybe 4%)
6) = what you have to live on
#3 healthcare expenses is the bigee. I think on Obamacare, it could range from $800 to $1,400 a month.
In theory, we can retire now. In reality, we want to work 1-2-3 more years to add to buffer and wait till kids are out of school and on their own.
Check out
financial independence / early retirement. Lots of good info there.