Ok, under FL law, (FL Statutes 83.53) the landlord has a statutory right to access to the property with proper notice to show the property to prospective purchasers. The notice period is no less than 12 hours..
So FL is apparently pretty landlord friendly when it comes to access. This is the exact statute:
83.53 Landlord’s access to dwelling unit.—
(1) The tenant shall not unreasonably withhold consent to the landlord to enter the dwelling unit from time to time in order to inspect the premises; make necessary or agreed repairs, decorations, alterations, or improvements; supply agreed services; or exhibit the dwelling unit to prospective or actual purchasers, mortgagees, tenants, workers, or contractors.
(2) The landlord may enter the dwelling unit at any time for the protection or preservation of the premises. The landlord may enter the dwelling unit upon reasonable notice to the tenant and at a reasonable time for the purpose of repair of the premises. “Reasonable notice” for the purpose of repair is notice given at least 12 hours prior to the entry, and reasonable time for the purpose of repair shall be between the hours of 7:30 a.m. and 8:00 p.m. The landlord may enter the dwelling unit when necessary for the further purposes set forth in subsection (1) under any of the following circumstances:
(a) With the consent of the tenant;
(b) In case of emergency;
(c) When the tenant unreasonably withholds consent; or
(d) If the tenant is absent from the premises for a period of time equal to one-half the time for periodic rental payments. If the rent is current and the tenant notifies the landlord of an intended absence, then the landlord may enter only with the consent of the tenant or for the protection or preservation of the premises.
(3) The landlord shall not abuse the right of access nor use it to harass the tenant.
So here, if you are providing reasonable times throughout the week for the landlord to show the property, then I would opine that it would be reasonable for you to prohibit access on the weekends as this would bump up against your legal rights to "quiet use and enjoyment" and "exclusive use and possession" that are inherent under the lease.
If the landlord tries to bully you, you can always tell him that if he enters without your permission, you will call the police and have them appear and escort anyone off the property and file a formal complaint for harassement. When faced with the prospect of having potential purchasers confronted by the police, or working with you on times where there won't be any conflict, the landlord will normally choose the latter.
As an aside, in addition to being an attorney, I have also been a landlord for over 26 years and a licensed Realtor for 12 so I have seen this situation play out from all angles..