I've never had trilyte for prep-I've had something called Go Lightly, and the best flavor in my opinion is lemon.
Honestly, most people here would agree the prep is the worst part. Get yourself some Tucks pads, Prep H and some good trashy magazines to read in the bathroom, plus whatever kind of aerosol fragrance you like, maybe a candle. Alot of people like their IPods and Laptops,too. When you're prepping, be sure to wear stretchy pants, preferably with an elastic waist, because once that prep kicks in there's not alot of time for messing around with buttons.
The day of your colonoscopy, be sure to take off any fingernail polish and wear clothes that are easy to get on/take off and are comfy. Slip on shoes are a must; also undies that are cotton/comfy/you don't care what happens to.
Do you know if your going to get a local anethesia? I recommend this, especially for the first one, if you are really super nervous-makes it much easier on you. Don't hesitate to ask your doctor, but do it ahead of time, like a few days before. You basically go in, get the meds and when you wake up its over. If you have alot of gas, don't hold it in, just let er rip; they introduce air into the bowel and if it can't come out it makes you uncomfortable.
You might have some abdominal discomfort afterward, so keep Tylenol on hand, a heating pad is great, too. Even though you're starving, try to eat a mild, smallish size meal right after; you can always have more later-nothing with alot of fiber, or hard to digest til you know how you feel.
Best wishes on your colonoscopy-hope all goes great! Keep us posted!