I've got three different types of protein powder right now. For a weight gainer/meal replacement I use Cytogainer made by Cytosport. Three scoops gets you almost 600 calories which makes a perfect snack when I can't prepare a full meal.
I also use two protein powders made by Optimum Nutrition. The first is their 100% Whey Gold Standard. If you don't already know, your body absorbs whey protein very quickly making it one of the best types to take in the morning as well as before/after a workout. The other type I use is their 100% Casein Gold Standard. Casein is absorbed by your body at a slower rate, making it ideal for use later in the evening and before you go to bed.
This brings me to another important topic. Fueling your body before you rest/sleep. Make sure you are getting a minimum of 7 hours of sleep a night and try to keep a set sleep time. Doing so will allow you to set up your meals during regular times. To get to my original point though, your last meal should be about 20-30 minutes before you go to bed. Make sure to never skip this meal! It's almost as important as your first meal of the day which should be no more than 20 minutes after you wake up.