+1 for the 700p, I own one and love it, I shoot it at a 1000yds without any modifications. The rem 700p is a good choice because all the info needed for getting all the potential accuracy is easily available.
In regard to a semi, I used to own a M1A super match.
It is a very nice gun to shoot, very accurate, but requires alot of maintenance($$$).
Also this gun was not design to shoot with optics, so some $$$ is needed to upgrade the rifle.
In my opinion and also my next project, I will choose a AR10 plateform for a long range semi, probably in 260rem.
I own an accurised AR 15, and it is hard to beat for accuracy and ease to maintain. Lots of after market accessories to upgrade without the need of a gunsmith.
The down side of this choice is that the AR plateform is restricted, but I decided that the gov. would not compromise my choice of quality firearms.