You say you get a lot of PTO due to last minute vacations. Does it work out pretty evenly? Because they are being fairly generous with you they may be expecting you to also be generous. Personally, I would prefer money in my hand to unexpected and unrequested days off.
It doesn't sound like they are asking whether you are willing to work extra hours but I respond to the directive as though it were a proper question:
- Thank you for asking me before seeking a back up sitter. I am not available this Tuesday but in the future I could have some availability. OR
- I love spending time with DC and I know it would be fun, unfortunately I have a standing commitment and am not usually available after hours. OR
- We were so lucky that I was able to do it the last couple times but I am not able to anymore. Oh, why? I have another obligation. Sorry. OR
- After giving the early morning routine a test run for the past few days I have found that it doesn't work well for me. I am not as well rested and I don't want to burn out