Real Time Clock: DS1307 sounds like the best one to go with.
Some people will be groaning 'here we go again' but DS1307 can be a bit hit and miss accuracy wise. I have one of these and it looses 6.5 seconds per day. I also have DS3231 and that is good to 2 seconds per month. Depends on what you want it for and if you happy with the accuracy. A bonus with the DS3231 is the on chip temperature measurement but it does not have spare memory like the DS1307