I use 2 1/4" - 6" white glow in the dark tube jigs with 1/2 - 1 ounce jig heads. Every lake is different but usually I find them between 40-80' deep. If you want to fish Lake trout effectivly, my best advice is to buy a vexilar, doesn't matter which one just get a vexilar and your catch rate will jump up. The small fish (23" and smaller) hang out on the bottom but once they get big enough to not get eaten by the other lakers they can be anywhere from the bottom to 5' under the ice.
Granby is a great place, you can also try williamsfork or granby. I guess either way you drive they are all about the same distance from you. You may want to try that big res. near the junction of 9 and 1-70, that may be the closest to you for lakers.
Mntman
"Hunting is where you prove yourself"