I suppose you could set a minimum stay of 30 days or 60 days, but I don't know how it would work if, for example, someone books their 30 days starting 6 weeks into the current year, and then the next person books a similar stay but it starts 4-5 weeks after the current stay? I'm thinking with Airbnb you could wind up with some gaps if you had on instant book, so it might be best to have it off if you are trying to book longer term stays with short/no gaps between.
I am currently renting to someone for a 3 month stay. They first came as a two night guest on Airbnb, and they were very kind and so I offered my place for three months after meeting them because they couldn't find another place. However, we have a private lease because I am not absolutely clear on how Airbnb handles longer term stays. My lease has very specific guidelines for how damages are handled, payments, terms for eviction, etc. I know it meets the requirements of a lease for my state and would be enforceable in court if I had to go that route. So far it has worked really well and I kind of prefer it to hosting guests. I charged him as much as I could make in 15 regular Airbnb stays, because that is about what I was averaging a month. But it is much less work for me to have the long term guest because I am only laundering once a week, and the lower frequency of turnover makes things less stressful as far as keeping the house super clean (I have kids, they have stuff, school starts next week - it's nice to be able to have a little clutter without feeling bad about it).
I guess the best way to price your place for a monthly rental is to look at rental rates for your area and price competitively. I do think it is interesting that in a way Airbnb creates it's own rental market because someone looking for a longer term rental on Airbnb isn't necessarily looking at local rental rates. Anyway, you can set a % monthly discount that equals that competitive monthly price.
