The Eastern will have three sea days, the Western will have two. I think the Eastern will have more ports that are good for just beach days. I haven't done Disney's Western yet, will in January, but I did the Eastern in December. We had calm water and the ports farthest away had warmer water. Castaway Cay wasn't too cold either. This was over Christmas. I went early December to the Bahamas and it was freezing cold, but Florida was having a cold front so that probably contributed.
I think Eastern would work well if you want to spend most of the time at the beach, and it'll be something new to experience.