There’s pros and cons to both methods, different laws in different states can affect how much better one is than the other. In general, though, I prefer to just have one pool of PTO; hell, I’d prefer to have vacation and flex time in there too.
The benefit of separate sicks days is that, in general, they can’t tell you no. Maybe they can require a doctor’s note, particularly if you do it often or several days in a row, but if you’re sick, you’re sick. I’ve seen situations where it’s all one pool, someone requests a day off and it’s denied precisely because they have to control for people calling in last minute, whether sick or because they didn’t bother to plan it. But if you have to schedule it ahead of time to use it then, unless too many people have also requested it, you’re good to go. That’s the problem with the single pool, it sort of creates the opposite incentive to never let them know until the day of over risk of getting denied.
That all said, I still think the benefits of a single pool works better. As long as it’s not abused, there’s no reason to deny people a called in day, sick or otherwise. If certain people are abusing it, create special rules for them, like requiring a doctor’s note, and let everyone else just keep going as usual. The benefits are obviously that if you don’t get sick, or can work from home when you are, you get more vacation days or you can save up some and use them in an emergency if you do get really sick to cover until you can get short-term disability or whatever.
And like I mentioned above, I’d like to actually have holidays and flex time built in too. Sometimes I’ve had to work on holidays and then I need to go through extra hoops to use that day later. I’d rather just let it be left to me to use the day off when I want. Or if I need some extra time off earlier in the year, I can use it then and either repay it with what would have been vacation later or take no pay later. Either way, more flexibility.
And the same for flex time. It’s annoying if something comes up at the end of a pay period, particularly if there’s a lot of overtime one period and some needed time off on another one. Obviously probably needs a certain amount of oversight, but some days I’m able to stay busy well past my 8 hours, and if I know I’ll need a day off for something the next pay period, I may rather have the vacation time than straight pay, or worse un-comped overtime.
Either way, my advice to the OP is to just see how much of the sick leave you can reasonably use up by the end of the year. When’s your next dentist appointment? Make one in the next couple months. Have you had a physical lately? Maybe a day where you would want to take off but would typically work, like allergies or a cold, you can call in. I’ve known plenty of people who will use vacation for that sort of stuff. And, IMO, if it’s yours to use before the end of the year, there’s not any ethical issues with using it, as long as you’re not dishonest, like calling in sick then just sleeping in and going to a movie.