Agile Store Locator has beautiful Geo-Location dialog that appears on the page load, it has two unique dialogs that can be set from ASL Settings.
Geo-Location dialog prompt user to clicked on the "Get Current Location" button with an editable message, once the user clicks the button, his current location is shown on the Google Map with a marker, all the store list is updated with the distance to his current location.
Shortcode for the Pop-up is [ASL_STORELOCATOR prompt_location="1"].
Type your location dialog prompt user to enter their current location into the address text field with Locate button, the textbox is loaded with Google Place API, so when a user enters the address, it shows the list of possible addresses, and allow a user to select the right one. This dialog works well for sites where SSL is not installed because the first dialog needs SSL to be installed on your WordPress site.
Shortcode for the Pop-up is [ASL_STORELOCATOR prompt_location="2"].