We have stayed twice at POR with 5 people, myself, my parents, and my two kids (last trip the kids were 7 and 10). We LOVE POR! It has a very relaxed feel and you can catch a scenic boat to DTD instead of taking a bus. Also, the breakfasts at Boatwrights are the BEST I've ever had. I believe it's the only moderate which officially accomodates groups of 5 (I have read threads about others who have gotten a rollaway bed in other resorts, but we were told that POR was our ONLY option for 5 people in one room unless we went with Deluxe). The rooms in POR Alligator Bay section have two full size beds and one has a trundle which rolls out from underneath the bed closest to the door. I personally slept on the trundle a couple of nights and it was comfy enough. My mom forced me off the trundle and back into the bed with the princess of elbows and knees (aka my 7 yr old daughter). My 63 yr old Mom also thought the trundle was comfy. Other great features of POR include "legal" pool hopping to POFQ, yep you get twice main pools for the price of one, plus 5 quiet pools around POR and Bob Jackson the all ages Piano Man in the River Roost Lounge (he's a hoot).
Anyway I hope that helps some!