@Valerie696
I also host long-term guests. I can't tell you what a reasonable fee would be as my listings are individual rooms in a shared house, not a four bedroom house.
I have never charged a one-off cleaning fee either to short or long-term guests. I just factor it into my price. Maybe that means I'm not priced competitively, but as a guest I hate having lots of extra fees added on. Also, I don't want guests to think that because they paid a cleaning fee, they don't have to lift a finger. In a shared listing, it's really important that people clean up after themselves to a certain degree.
In terms of on-going cleaning, I have weekly cleaners come in to do the communal areas once a week and I keep them tidy in between. The guests do not pay extra for this, but they are expected to wash their own dishes/put them in the dishwasher, wipe down kitchen surfaces, leave the bathrooms reasonably tidy etc.
As for their bedrooms, they are given the option of either cleaning them themselves and then supplied with extra linen/towels and cleaning products, or I can clean them (usually fortnightly) for a small fee. Funnily enough, female guests usually opt to do it themselves and male guests are always happy to pay you to do it!
The one downside with this is that not all of the guests who opt to do it themselves actually do any cleaning. So, I have started to offer the first clean free. This means if someone is staying 3-4 weeks, the room doesn't get too dirty. If they are staying longer, it gives me the opportunity to see how clean they are keeping it or not and I can then approach the matter accordingly.
I know this is not so specific to your situation, but perhaps it helps.
