Do you share a hotel room on other trips? When my kids were young, we could do it. Not ideal, but saved money. Now there is no way I could; we get two rooms since they were about 7 and 9. I have a boy and girl, and my son kicks in his sleep, so it is hard! No one wants to share a bed with him!
Many folks are fine with it, but only you know your family.
I get up early, even on vacation, so make my coffee (value resort doesn't have the coffee maker, but I'm bringing one - other resorts do have them) and take it either in the bathroom or patio, or wherever I can in my jammies, and have my morning routine of coffee and reading the news on my ipad or phone). I try to not wake anyone - I can usually shower and dress and they're just waking up!
I'm sure you'll be fine, long as the double beds work. Most kids are tired out from the excitement of the day, and crash!