The important thing to remember is that these are *requests*. Some can be met, some cannot. If your room assignment isn't what you were hoping for, you can always go to the front desk to ask if they have a room available that will work better for you. Sometimes they'll have something available, sometimes they won't.
This is the most important thing to remember. They generally try their best to accommodate the requests, but sometimes they just can't.
As stated above, making the request as simple as possible - keeping them to 2, 3 things max - and letting them know your priority order helps.
For example, my upcoming stay is at Sports in a Preferred room. My request sent via Touring Plans includes:
"I would like to request a room...
1st priority - Surfs Up section
2nd priority - 3rd floor
3rd priority - Corner room"
That way the room assigner can look if there are any available rooms in Surfs Up, then if any of those are on the third floor, then if any of those are corner. Ideally there would be a room that met all 3 of those. If there are no corner rooms but there are 3rd floor Surfs Up rooms, ideally one of those. If there were no third floor rooms but rooms in Surfs Up, then ideally one of those would be assigned. If by some chance there are no rooms in Surfs Up for whatever reason, they would go to the Touchdown preferred rooms and see if any of those were on the third floor and if any of those were corner. And so forth.
But I still understand it is just a request. Well, not the Preferred part - that I paid for so if there suddenly is no Preferred room, I'll be politely discussing options with the front desk.