As far as using drugs to help with uncomfortable trips, I would only use a benzo if I was really starting to panic, because it will cut the trip down by far the most (out of benzos, opiates and alcohol). Opiates will leave the trip more intact but just make you feel good and less anxious because that's what opiates do. Probably not as good at stopping a panic situation though, but a better bet if you're just really feeling uncomfortable and it's ruining the trip. Alcohol can go either way... I find it will really ruin the clarity of a trip worse than benzos or opiates, but a little bit can be nice and relaxing. I like to drink at the tail end of a trip, after the peak effects.
Ultimately the best thing to do is usually to ride it out, it helps you to learn to deal with intense situations, it can make you a stronger person, and you can learn things about yourself. A lot of the time, difficult parts of trips can go away when you work through them and then the trip becomes great.