Hi, Julie!
Welcome back to the Disney Parks Moms Panel. You are going to love staying at Disney's Beach Club Resort -- fantastic location and arguably the best pool on property!
The Beach Club has 583 rooms so, believe it or not, it is actually a relatively small resort by Walt Disney World standards. (Disney's Port Orleans - Riverside and Disney's Art of Animation Resorts each have more than 2,000 rooms!) I think what makes Beach Club seem like a larger resort are the adjacent Beach Club Villas (the Disney Vacation Club section) and the Yacht Club -- it appears to be one huge building, but is actually comprised of several distinct sections.
The water view rooms look out over Crescent Lake, Stormalong Bay or the Tidal Pool. Some rooms feature full walk-out balconies while others do not, so if a balcony is a priority for you, be sure to request this.
As far as your actual room location, if you'd like to be nearer to Stormalong Bay (the main swimming complex), the Boat Dock and table-service restaurants, you'll want to request a room closer to the Yacht Club side. If you prefer a somewhat quieter location (farther away from the feature pool area) would like to be closer to Epcot, then go ahead and make this request.
I don't necessarily recommend requesting specific room numbers, but the following rooms have full balconies and the best water views (of Crescent Lake): 2641-2647, 3501-3511, 3683-3691, 3725-3795, 5607-5623, 5683-5691 and 5725-5795. Please keep in mind that room requests are not guaranteed, but Beach Club's room assignors will do their best to accommodate you, based on availability.
Wishing you a magical vacation! Please write back if I can assist you further in planning your "Disney time".