PT- treat, sticker chart or other rewards

DS has shown she understands what the bathroom and toilet is for, she is 26 months and actually has been pooping on the potty since around 16 months(we found she didn't like going in her diaper so she would hold it and would get backed up so we put her on the toilet one day and she went so we started doing that when we knew she had to poop). Sometimes at night when she doesn't want to be down for the night she says she has to go pee on the potty and she knows that we will take her there and then she thinks its play time, but on occassion she does pee so i don't want to ignore her requests.

My question is what kind of reward should I use. I know some people use food treats others use sitcker charts. I am leary about using food treats because if she asks and uses the toilet right before bed I don't want to give her a sweet treat and have her be up. Or like the other day she said she had to use the bathroom right before I made breakfest, again didn't want to reward with a sweet treat. The problem with a sticker chart is we haven't had stickers for her before and i am not sure she would see that as a reward. But I do want to start rewarding her for telling me she has to go and then actually going(which will be helpful when there is a babysitter, she refused to go poop when she desperatly needed to the last time she had a sitter). I am also interested in other types of rewards people do to encourage continuous asking and using the bathroom correctly. I was thinking in correlation to the sticker chart that for so many stickers she gets she will get a big prize, like a book or a small toy(we stash away happy meal toys when we eat out for stocking stuffers and such). I would like the reward to be consistant no matter what time of day.

Sorry if this was confusing and yet another post on PT, but I am not on here much and with her interest I have a lot of questions for those with experience because my friends with kids have kids younger then DS and have no experience with PT.