Need some suggestions

Here is the situation. I will be installing a wireless network at a beach club.

-Wireless acess point should be outdoor access points.
-I need BASIC ENCRYPTION. WEP or WPA
-The distance from the building is 375ft
-The distance from between the 2 sides of the property is 300ft

-I can install a few access points, but I would really like 1 SSID. (Bassically the user need the ability to walk from one end to the other streaming video without the connection breaking)

It was suggested to me to use some type of mesh(?) network but i'm not exactly sure what i need to accomplist this.

-I have a great deal of finances at my disposal, so i'm not worried about cost. The cheaper the better however, but it need to be reliable.

I was looking at an Engenius WAP with a 10dbi omni antenna, but i'm worried the laptops will not be able to talk back at that distance.

Any help or suggestions would be great.