If it's your first play through... then you probably can't distinguish the new content. I would install the unofficial patch for bug fixes, and play the vanilla game through to the end; then install the restoration patch for use with the next character.
RP adds even more content to this already huge game and makes it harder, so I'd say it's better to see how vanilla feels first. By the way, the new locations in RP always felt a little off to me, maybe because I'm used to vanilla.
vanilla is already huge with alot to do, i couldn't get the RP to work properly when i tried it but i played vanilla fallout 2 probably 20 times all the way through lol