How to display View contents in a drop down select list?
Sure this is all possible:


If you just want a select list assure you have the Ctools module installed on your site and use the Jump Menu views style output for your Partners content type. Alternatively use the Jump Menu module which you may find more helpful.
Want this embedded into a block you say? Use the Views Field View module to place your output of (1) into a second view that is a block. If you go this route you likely want to enable caching in your Views.


Be sure to see the project page(s) for these modules.