9-10 hours @ 225 degrees should do it for you if you have a 20lb turkey.
30 hours on a brisket sounds fun. Most of the time I smoke a brisket 5 hours unwrapped and 4 hours wrapped. I brine the meat for 2 weeks(garlic, onion, salt, pepper, red wine, apple cider vinegar, v8...) and then dry age it for a week before smoking it.
Not sure if you have access where you are but i would recommend smoking Tri-Tip. Make sure you purchase it untrimmed because the fat cap is necessary. It is a popular cut here in southern California but can be hard to find some other parts of the country.