One of the blogs I follow is Dave MacLeod's Page F30, which is mostly about languages (including auxlangs) and astronomy. He also shows up on Auxlang a lot and isn't locked in to just one auxlang. At various points he has advocated Dracula as a translation project.
No. Let's stake this idea here and now.
* Length. Seriously, even in an at-sight auxlang, Dracula is a bit long. Serializing would help somewhat, but it's an actual novel (and nineteenth century, too), which means it has pacing appropriate for fluent readers. If you're familiar with the story, there's building tension in the first chapter that works really well, especially if you somehow don't know what Dracula is. But it would be tedious for a learner.
* Vocabulary. This, as they say on Monty Python, is the cruncher--or one of them, anyway. The terminological traps are legion: geographical fine points to begin with, but also architectural, medical, and nautical jargon. There are also a lot of letters, including period business correspondence. Ouch. Right off hand, I'd say that the only auxlangs I'd have any chance of translating Dracula into would be Esperanto and Interlingua, with a slight possibility of Occidental. In Eo I could work around the lexical problems by compounding, which is also a possibility for Occ. For Interlingua, I could use some existing translations into Romance languages as guides. (I couldn't translate Dracula into Spanish or French very well, either: I haven't the specialized vocabulary and the result would sound stilted.)
* Basilect/dialect issues. This is almost Vocabulary II: The Sequel, but there's more to it. Once Drac comes to Britain, we begin running into some amusing bits of dialect and basilect:
"I'm afraid, my deary, that I must have shocked you by all the wicked things I've been sayin' about the dead, and such like, for weeks past, but I didn't mean them, and I want ye to remember that when I'm gone. We aud folks that be daffled, and with one foot abaft the krok-hooal, don't altogether like to think of it, and we don't want to feel scart of it, and that's why I've took to makin' light of it, so that I'd cheer up my own heart a bit. ..."
Translate that (preserving the feel!) if you can.
But the other problem is that this would be dangerous for anything but a mature auxlang. How do you render "I've took to makin' light of it"? Perhaps (in Eo) "Mi 'as ade ma'gravigi tion"? This is nonstandard usage, friends, and that should be reflected in the translation. I might even drop the accusative. But beginners, especially in a young auxlang, should not be confronted with nonstandard usage: they're trying to get a grip on the standard language. (For this reason, I wouldn't use the English original with people learning English, either.)
This leaves an obvious alternative, however. I'll turn to that next.