By the end of the game, most people reach a character level in the mid forties to low fifties, if they explore everywhere and do the majority of the sidequests. Even doing everything, maxing Wisdom, resurrecting a bit and delaying taking the level bonuses (to maximize the experience points gained), it would be difficult to get higher than level 53.
In a game trying for the lowest possible character level finish, Ariana was level 17 at the start of the wastelands (about 90% through the game). This involved a great deal of saving and reloading to get through the required fights, so she quit at that point.
