Hi,
I have been developing websites since 2008, a number of them being directories. Lately I completed a revamp project here on freelancer.com for a business directory in Canada which involved displaying the listings on an interactive map, I expect your needs to be similar and I suggest you check my reviews.
For that project I used Joomla and a CCK (Content construction kit) called Seblod. Both are free, opensource and run on php and MySQL. They also support multiple languages. They would be a good fit for your project too. It will allow user to register and depending on profile (landlord, tenant) capture information (listing, search criteria)
It would be helpful if you could share your design ideas as it would help me assess the project workload fully.
Do not hesitate to contact me if you have any questions.
I look forward to hearing from you and start working on your project.
Regards.
Xav.