how to create a taxonomy Views combining terms from 2 different vocabulary
By default, Views Taxonomy page allows you to select multiple terms.  If you click on the Contextual Filter &quot;Content: Has taxonomy term ID (with depth)&quot;, one of the first choices you see is whether to allow multiple values.
Let's say that these categories have the following term IDs:

Destination Vocab:

dest1 [25],
dest2 [26],
dest3 [27],
dest4 [28]

Category Vocab:

cat1 [35]
-- subcat1.1 [37]
-- subcat1.2 [38]
cat2 [36]
-- subcat2.1 [39]
-- subcat2.2 [40]


If you want a page to show you all items in category 2 for destination 3, you'd have a url like this:  http://www.example.com/taxonomy/term/27+36.
To limit the allowed Vocabularies, open that same Contextual Filter &quot;Content: Has taxonomy term ID (with depth)&quot; and scroll down to the section &quot;WHEN THE FILTER VALUE IS IN THE URL OR A DEFAULT IS PROVIDED&quot;.  There is a validation section where you can check off the vocabularies that you want included:

taxonomy validation http://www.emijayne.com/sites/default/files/linked/taxonomy.jpg