Lets start at the stern (the back). This is the main deck for the Aquatheater.
You can only access the Boardwalk zone from the inside, slightly to the stern of mid-ship. This is so when there is rough weather, like we had on our last day, they can close it off. What this means though, is that if you're in one of the rooms that are on either side, heading towards the stern, you have to walk up ship before being able to get to your hallway.
Once inside, the mid-ship zone includes the future sales office, Focus (where you get those pictures they're always taking on the piers), the Schooner Bar, and the Diamond Club. Of course, you can't access any of these (or their stairs down to the Royal Promenade) from the cabin hallway.
Up at the bow is the main entrance to the Vitality Spa and Fitness Center. We had a tour, but nothing is free. On smaller ships, my inlaws told me they would go to the fitness centre to use their (larger) showers, but you can't seem to do that on this ship. If you are on the walking track on deck 4, you can enter the fitness center and go upstairs, take a little shortcut.
There is no access to the helipad at the front of the ship, though I think you can take a ($$) sunrise yoga class on it.
"Long Stretch of Lonesome" (Patty Loveless) is playing in my head, alternating with "I Would Walk 500 Miles"....However, I do think it would have been more upsetting to have a room right down at the stern, behind Johnny Rockets, and have to walk 1/4 of the way up ship to just turn back to walk the same distance! Perhaps Royal should think about this. For little kids and the elderly, it's a LONG way just to get out of the hall!