300WBYMAG

You can see what my choice would be from my ID, but I also shoot a 270 WSM. You seem to be hinting towards longer shots and like the other said, if you practice and get accurate, you can shoot at further distances. If that is the case I think you would want to avoid the 30-06 because of the bullet drop at distance and the velocity lost down range. I really wanted the 270 Wby Mag but because of price I ended up going with the WSM. They pack more umph down range then people are giving credit here (wby more so then the wsm). Look at the ballistics of the rounds and compare the 30-06 to these rounds at 300 or further. Last is personal experience. My buddy had a late rifle tag last year and we ranged the young 6x6 he shot at 540 yards. He took one shot with his 270 wby mag high shoulder and dropped it where it stood.

I finally broke done and bought a Bogen setup about 6 months ago and couldn't be happier. I have the 3021BN tripod with 3130 fluid head. Paid $ 180 at B&H Photo. The things that I see as a must for hunting/scouting tripods are: Adjustable angle legs for uneven terrain, one that is tall enough for your height (I'm 6'4" so I had to go with their tallest model), one that is sturdy because of the abuse in the field, and a fluid head. If you haven't yet, go to a photo shop and try panning with different kinds of heads. My old tripod was a ball head and I'll never go back after using a fluid head. I also would be wary of the carbon fiber models. I had two friends buy them and return them after one glassing session. They were hard to keep steady in 15mph+ winds and would shake even with some monster 20x Doctors mounted on top. With my setup I am able to handle the weight of my Leupold GR spotting scope w/ a camcorder attached to it with no problem. That is at least 10lbs, exceeding the recommendations but working fine. That would handle your 15x56 fine. But really look into the fluid head and adjustable angle legs. I think you would regret not getting those features.