A lot of the responses are saying the 7mm mag is a good choice but to look into the 300 mags. I agree with all of them, including the ones that say the 7mm. Personally I would rather a 300 mag. Either the 300 Win Mag or 300WSM if it were my choice. A good 180 .308 cal bullet is hard to beat ballistically and has plenty of oomph for anything on this continent. My friend uses a Browning Titanium in 300WSM almost exclusively and has taken 23 of the 28 big game animals in NA with it including a huge brown bear using Nosler Accubonds in 180 gr.
Unless you use a 300 ultra mag you are not going to see any difference between a 7 rem mag or 300 win mag certainly on deer and more then likely on Elk provided you use the right bullets. I base this on years of shooting both at big and medium game.A lot of people will differ on this opinion and I am ok with that as well since everyone has a comfort level with certain cartridges. If your going to be shooting deer with the occasional elk then by all means get a 7 mag in some flavor , put a scope on it and go kill something. I wouldn't even dream of using a 300 win mag on the largest Bears ..that would be a 8MM Remington 325 wsm and up exclusive territory.