I play in a game with friends and they have allowed my son to join in.  He is a mature young man.  No problems for anyone.

He is playing a paladin with a Noble background.  He plays this character as a noble that recognizes he has responsibilities to the common folks and all that, but he was not born high enough to have a great inheritance; thus he has decided to become an adventuring paladin.  He has selected the Wealthy lifestyle because our DM required it of each of us, and my son was not allowed to dip below wealthy (aristocratic is above that, right?).  My character is living at Comfortable, the next step down.

My son's character travels with me as a guard from time to time, and I enjoy RP that out of respect I provide him with the best accommodations we can find as we travel from one town/city to another.  I can't always find him accommodations that are up to wealthy standards, but I give him the best I can find.  I always take Comfortable or the best that I can find when Comfortable are not available.  My character doesn't "wait" on him, but I often hire an attendant to travel with us as well, and I will ask him to provide some service to the noble man.  Of course, this hired hand will take care of our animals and stuff like that, but our hired hand knows he needs to check on the noble man once in a while just to see if he can do something for him.  My son doesn't make a nuisance of himself but accepts the help in getting his armor on in the morning and stuff like that.

Does anybody else RP being a noble?  Or is that quite out of the ordinary?

Some of my favorite characters have been nobles. I had a 3e character who had a servant just for rp purposes. He’d help my character change clothes, bring over a chair when I wanted to sit, absurd things like that. It worked because it was pure rp; never in fights or rp situations, could never do anything useful. It was super fun. 
I had another recently, a rogue, he was just entitled and oblivious to the idea that someone might ever not be rich. 

I remember our party had a nobleman with a servant named Pennel. He was basically our human pack mule and we ran him pretty much like Xalthu above, except occasionally if there was a fumble during combat, whoever was DMing at the time would narrate the stray eldritch bolt or whatever as hitting him as he cowered in the background. He died a lot. It was years ago but whenever we see the mini we think fondly of Pennel. Not sure if it was mutual though.

Just started running a new noble character, our first adventure has us washed up on an island so I'm not having to worry about the price of a five-star inn yet, but a bit concerned that my starting purse of 25gp won't last long back in civilisation. 

I have a young paladin that grew up as the daughter of a minor-middle noble (Viscount) and knows how to behave and function in that world. However, she is more interested in her oath of vengeance than sleeping in a feather bed. She has high standards for accommodations, food, dress, company in town when not with the party, but has no problem roughing it on the road or in the field. For roleplay, she will seek out gentry and nobles, talking to commoners only when necessary. However, she will come to the aid of anyone accosted by evil doers. When she attains knighthood we'll see about a man-at-arms or two and a servant as she levels. She is more interested in earning her spurs, getting a destrier and full plate!