Hi Malinda!
You are going to LOVE
Disney's Beach Club Resort. I just stayed there with my family for the first time and we all thoroughly enjoyed it!
For a great view of Crescent Lake, I'd recommend that you initially book a Pool/Water View Room. Once you're booked in that category, your best bet to secure the view you're after would be to call in and request a note be added to your file. Here you can put in your "request" for specific views, room numbers or range. Keep in mind of course, that this is a request and cannot be guaranteed. Disney Cast Members will do their very best to accommodate your request within the booking category you've reserved and based on availability upon check in. Re-confirm your request with the Cast Member who checks you in on your arrival day.
To achieve both a high floor and great lake view, have a request notated on your file to be in odd-numbered room in 5607-5623, 5683-5691 or 5725-5795.
I hope this helps you out and that you enjoy a fabulous time at Disney's Beach Club Resort!
Wishing you a Magical time at Walt Disney World this fall Malinda!
Kirsten