Almost the entire 10 mile stretch of OC has hotels and condos ocean front that you can walk from your room over the dune onto the beach (a 50 yard walk or less!).
If you are looking for a condo, most realtors websites let you do what you are looking for. Two
realtors I've used in the last few years and been
very happy with are:
Coldwell Banker: 800.633.1000
http://www.cbvacations.com/ Shoreline Properties: 800.492.5832
http://www.shorepro.com/ If you want a hotel
This website on ococean.com lets you search by area and amenity, but not by number of people and
this website on oceancity.com lets you search by number of people and amenities.
My favorite section of town is midtown, between 30th and 80th Streets. This area features mostly low rise buildings and tends to be less crowded. In this mid town section the more crowded blocks are 48th - 50th Street (Gateway Grand and Ocean Pines beach club are there), 58th Street (Sandpiper Dunes), and 67th Street (Holiday Inn, Sunset Island). However, note that crowds can vary block to block quite a bit. For example,
67th Street is more crowded because of the people from Sunset Island and the Holiday Inn, while crowds are smaller just a few blocks
in either direction.
This thread has more info about OC's layout and the best areas to stay. Have a great trip to OC!