Actually, You should avoid requests like "near the lobby" or "near an elevator." Over the years because of the incredibly far distances that many rooms are from the lobby (the building is about 2/3 miles long), near the lobby has become the most prevalent request with the result that many do not get it and are then just placed in any available room, which is often very far from the lobby.
As to elevators, there are three spread out over each of the two wings, so that every room in the building can be considered "near an elevator." Thus, if you request simply "near an elevator," you could be placed in any room in the building. What you need to do is request being near an elevator by specifically naming the elevator you want. If you want to be close to the bus station on the south wing and within reasonable distance from the lobby and pool, request "near the Timon elevator." If you want to have the shortest trip to the pool on the north wing and be within reasonable distance of the lobby and bus station, request room "near the Rafiki elevator."
As to the lower or higher floor, lower gives direct sight toward animals while higher more panoramic and personally I never request floor because either view is fine.