If Louis had one skill, and only one skill, it would be talking. Boy, can this guy talk. He's the type of guy to whom you might say: "Do you just have all the time in the world to talk about yourself?" And his answer would be: "Yes."
Being immortal gives Louis the luxury of talking about himself for hours and hours on end. He loves to wax nostalgic about anything and everything. Take Paris (please, take her!). Louis's monologue about Paris perfectly evokes the feeling of being there in the 18th century:
We were alive again. We were in love, and so euphoric was I after those hopeless nights of wandering in eastern Europe that I yielded completely when Claudia moved us into the Hôtel Saint-Gabriel on the Boulevard des Capucines. It was rumored to be one of the largest hotels in Europe, its immense rooms dwarfing the memory of our old town house, while at the same time recalling it with a comfortable splendor. We were to have one of the finest suites… (3.6)
…and so on and so on. You can practically hear Louis pronounce the circumflex in "Hôtel." You realize that this is a dude who appreciates life's finest pleasures.
The only downside to this is that Louis establishes both his character and the setting early on. By the time he starts describing New Orleans or Paris for the 72nd time, you just want to shake him and say: "We get it! Let's move on to the biting!" But remember, as an immortal, Louis can reminisce and relive whatever he wants to, for as long as he wants to. We're just along for the ride. And he's got centuries of stuff to remember.