If I'm listing four things, three of which are female, would I say muchas or muchos?
Tiene muchos playas, montañas, tiendas y restaurantes
If restaurantes is male then do I start the sentence with muchos even though it's followed by the feminine playa ?
If you start with a female one, you start with muchas. If you start with a male one, you start with muchos.
In your example we have
Tiene muchas playas, montañas, tiendas y restaurantes.
Since restaurante is a male word, it doesn't change the sense of the sentence.
We can do an inversion like:
Tiene muchos restaurantes, playas, montañas, y tiendas.
But since there are more females than males, it's better to put first the ones in more quantity.
A more complex result is to have:
Tiene muchas playas, restaurantes, montañas y tiendas.
Here you have female, male, female and female. However since the first word was used with its correct genre, the sense of the sentence doesn't change.
It would sound better if you had restaurantes at the beginning of the list.
Tiene muchos restaurantes, playas, etc...
Mixed masculine and feminine nouns would evaluate to the masculine, so your sentence is correct, it just sounds odd to have the feminine noun first with a masculine adjective. It might sound a bit better if you said.
Tiene muchas playas, montañas, tiendas y muchos restaurantes.
