I am planning to be fulltiming and feel it is better to have one just in case. I am also new to RVing and purchased this ladder, see below. I have used it a few times to access the tops of the slides and was very happy to have one of my own and need to bother someone else to get one. I also have a ladder at the rear of the coach in order to get on the roof.
http://www.campingworld.com/shopping/item/telescoping-6-extension-ladder/69517
I like this model as it can be an extension or an a-frame ladder. Pricey but works well and is compact.
Stuart