I have not been at Luang Prabang yet. Let me add couple of points about topics mentioned above:

1. Avoid scoot. No, should be this way - avoid Scoot at all costs. If you decide to fly Scoot, makes sure that you are OK if you get to your destination 60h later. That's their latest record. In Singapore people even have an expression - 'friends won't let friends fly Scoot'.

2. Penang - been there twice, as well as in Langkawi. The primary and I'd say probably only reason I'd go there would be food, if one is fan of Peranakan/Cantonese/Malay (and other cousines) food. While Penang has some share of history and art (in forms of street art), that can be done in max two days and there rest in the whole island is not much interesting. Plus, serious traffic problems and occasional flood - last one couple of years ago was a serious problem. In terms of beaches - you'd better go somewhere else.

3. Da Lat - my favorite place in Vietnam. Way better/cooler climate than coastal places, excellent food, nature and things to do for a week, well, at least for several days.