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For the days that the whole house is rented, you would allocate 100% of the expenses.  

For the days that only a bedroom is rented, the most accurate thing to do would be to allocate expenses based only on the square feet of the bedroom divided by the square feet of the whole house.  Even though the guest has access to common areas as well, you are also there using the common area for personal purposes.  Therefore, you could not include all of the common area as part of the rental space.  For example, if the bedroom is 100 square feet out of a 1000 square feet whole house, the bedroom is 10% of the space.  Therefore, for days that bedroom is rented, you can allocate 10% of the expenses to that rental.  If the second bedroom is also rented, then you can add the percentage of expenses for that room on that day as well.

Since you are combining all of this as a single rental property, you will need some detailed records to back up your calculations.  You will need to show what part of the house was rented at any given time so that all the prorated amounts can be calculated and entered into your return.

You will need to count the total number of days rented for each of the three possibilities -- total house, bedroom 1 and bedroom 2.  Then allocate the total expenses to each one based on the number of days each was rented during the year.  Then add the three totals together to account for the whole year with regard to each expense category.

As you enter your information, do not rely on TurboTax to do any of the math for you.  You will need to enter your own information based on your own records.