Google Map setup for markers
Your first example essentially looks correct — and I don't know if it makes a difference, but the syntax that I have used in the past looks something like this, where I output the map after setting the data.

{% set options = {
    id: 'map', 
    width: '950px', 
    height: '500px',
} %}

{% set map = craft.googleMaps.map(options) %}

{% for entry in craft.entries.section('maps').limit(10) %}
    {{ craft.googleMaps.data('map', entry.mapData) }}
{% endfor %}

&lt;div class="map"&gt;
    {{ map }}
&lt;/div&gt;