I really like the name Laetitia because my mother's cousin has this as a middle name. Leticia and Letizia are good alternative spellings too, but I don't like Letitia. At least it would be more popular soon. For the pronunciation, I think this name should be pronounced as Læ-tee-sya since the "ae" sounds like æ in IPA (International Phonetic Alphabet, not Science in my language's abbreviation!).
This name brings to my mind a little girl who's happy all the time (unrealistic as that may be), smiling and charming (through childlike cuteness) her way into the hearts of everyone around her. That said, all three of its bearers that I know in real life are mature and pragmatic young women; that said, the one I know best out of the three has a funny side that she only shows to friends, so that causes what I know of her to partially match my impression of the name. What gives? In time to come, I might come to think of this name as one that ages well.