I rent out a one bedroom apartment above my garage, it's about 500sq.ft. and I charge a $20 cleaning fee.
If you're paying someone to do your cleaning, you should charge whatever you're paying them. If you do it yourself there are a few different pricing strategies based on what you want in a guest. If you want to encourage longer stays, having a high cleaning fee with a lower nightly rate will make a longer stay more affordable but a one night stay possibly unaffordable (or a huge perk!). A lower cleaning fee but higher nightly rate could net you the same amount of money but encourage shorter stays which means more work for you (I've had a lot of one night stays recently and think I will up my cleaning fee for the summer). A higher cleaning fee can also turn away bargain hunters by bringing your costs up just enough that they may look right past you.
Another question, is roughly where are you located? Even here in the midwest for having larger places and since you have 2 they're probably not next door to you, you need to charge enough to be worth your time. I would pay yourself at least $10 an hour since this is active income. So having a larger cleaning fee with a slightly lower nightly rate (passive income) would be good. Also to consider including in your "cleaning" turnover fee are any fixed costs that you supply for each booking: snacks, liquor, flowers, costs of doing laundry, etc.
But especially since these are houses and you'll probably have 3-4 people stay each time, that's 3-4 loads of laundry, 4-5 hours of cleaning probably, travel time, etc. If it were me I'd do at least $40 on the smaller house and $50 on the larger one, more if you're on a coast or a destination city.