Well for instance in your case, both Boot and Title screen look really good but a whole different thing is, do they match up with the contents of the hack. If Sienna revolves around Lugia, it makes sense for it being in both of those screens.
I know this is a bit nitpicking but as for myself, I'd like to add a neutral title screen to my own hack without anything special being shown in them if I don't get someone doing a game-related title screen for me. At least, no pokemon being shown in it would do.
This far, this is all I've got though which isn't much of a title screen but it was fan-made work by a person called RED and I really appriciate him doing that:
Pretty much gets to the neutral category of not showing anything about the gameplay but definitely a whole lot better than having Lugia flying around (talking about Pokemon Silver title screen that is).