mar1juana and alcohol are befuddlement agents. They can help you fall asleep, but often you don't reach deep REM cycles. You can also wake up in the middle of the night once the effect wears off. Withdrawal from mar1juana can also cause severe insomnia. There's nothing wrong in my mind about mar1juana or alcohol, but they are not cure alls for insomnia. A fair bit of research on sleep, show it is not helpful to consume high amounts of either shortly before you try to go to sleep. They can be amazing if you're traveling across time zones (especially if you're hopping across 4+ time zones). They help regulate sleep to light cycles. However, two caveats about it. It's not a regulated drug. You buy it as a supplement or vitamin, which means there's not a whole lot of regulation in regards to its content. You will also have super intense dreams. I was on the nicotine patch when I was younger, and I thought those were wild dreams. But they pale in comparison to dreams on melatonin. Melatonin is illegal to sell (not to possess) in a number of Eurpoean and African countries. I've got family members who come over to the States and make sure they buy massive quantities of the stuff to take home.
Don't take Melatonin (see previous post). That causes intense dreams. I don't think Ambien really reduces my dreams, but I don't often wake up the next morning feeling unrested from troublesome dreams. You might want to look into Ambien CR or one of the long-lasting versions that keep you deeper sleep throughout the night. There's also Lunesta. Since you have to see a doctor to get a prescription for it anyways, I would ask them which might be appropriate for dream suppression.
I wouldn't recommend Ambien or Xanax until you know how they affect you as both can cause AM grogginess. I'll sleep fine with 10mg of Ambien or .5mg (<--that's HALF a mg) of Xanax, but Xanax is the bigger culprit for me re: grogginess. If you want to go the medication route, give yourself plenty of time (1-2 weeks; longer if possible) to get used to the medication and talk to your doctor about this issue.
I don't know specifically about reducing dreams or dream intensity, but Ambien does enhance the deeper stages of sleep. For this reason, it is associated with higher levels of daytime functioning. So, you might see an improvement. It's worth a conversation with your doc, at least.
The only time I tried Melatonin, I was out for 2 days. I'd test it out before this event if you're going that route.
melotonin. start with one pill, see how you do, take up to three if you need it, no more. don't drink when you take it.