I cannot comment on geriatrics since I've never worked with that population. However, I give the utmost respect to nurses who do. It has many challenges and setbacks that people don't consider.
I've worked peds my whole career (8 yrs). I now work in peds onc. I love it, however, it is very draining. Some people are surprised that children die. Also, you're not just dealing with the child, you are offering support to their parents, siblings, grandparents, aunts and uncles, etc. You are dealing with people who have been dealt the worst of the worst. It is not something to consider lightly.