I am currently using all three heating methods mentioned (one for each cage) for experimental purposes. Here were my observations: with the UTH or heat pad, I found that while it provides belly heat and doesnt dry out the air too much, the heat it provides is too localized. While its warm directly on the heat pad, inches away its cold. It does not warm the air nor keep a smooth temp gradient across the cage. As far as lighting, I wouldnt use a bulb, but rather a ceramic heat emitter (lasts longer, wont disrupt photoperiod). The ceramic heat emitter does a great job in warming the air and surface, while providing a great temperature gradient from hot to cooler across the cage. Their drawback is energy consumption but more importantly it dries the air out too much even with a water source close under. The final heating source that I have implemented in my collection is the much endorsed (on this forum) radiant heat panel. This is my preferred method of heating. It mounts to the top and heats a larger area than a heat emitter, while consuming somewhat less wattage. Good luck, hope this helps. 
>>Oh man I'm real upset I just typed a big post and my internet went to hell and deleted it, so I'm going to have to make it short. Do any of you prefer lighting as your heat source or undertank heat? Currently all my herps have lighting on timers to simulate day/night, but now that its winter and they all live in the basement I'm a little worried about night temps. I recently have been installing undertank heating for all my young snakes, but I'm not sure what to use for my bigger herps in plastic cages. What exactly do you use that is safe with plastic? Is a 247 underbelly heat source OK? Any specific info would be helpful! Thanks.