A zoom is a lot more practical but not as high quality as a prime most of the time. If you were just going to get the 24mm by itself I'd say it's a bad idea, you need another lens or two along with the 24 to stay versatile. An 85mm probably.
24 still isn't crazy wide though, something to keep in mind. To go wider you usually have to go slower or way more expensive. Wide, just not super wide.
The Canon 24-70mm 2.8 is a great versatile zoom with high image quality and decent speed. There's a Sigma 24-70mm 2.8 zoom that costs a little less and those who use it rave about it (I haven't used it).
On the cheap, but still fast, side of things there's the Tamron 17-50mm 2.8. I have it, and it's a little soft and slow autofocus in photo mode, but it's a great-cheap-wide lens. Pick one up for $350 used, and I'd recommend it over the Canon 18-50 kit.
About the sunrise, you can use a slower lens for sure. And anything landscape usually does better wide.
Just a thought, you might rent these lenses for a weekend at borrowlenses.com or similar. Spend $100 in rentals and you'll have EVERYTHING for your short, then be a lot better equipped to make a purchase decision.