Anyone with experience driving in the Alps?

I will be RENTING a BMW for a week in the Austrian and Italian Alps and want to pick the 'best' BMW model for me. Wife and I are 50 somethings who like to enjoy great views from great roads. We have heard all the scary stories of Alpine roads being full of slow trucks, carts and Ferrari's passing everything. We want some basic comfort (4-6 hours per day behind the wheel) enough power to pass and feel secure.

Price wise the 1 Series is great but is it too econoboxy? The Z4 looks the part of Alpine Racer - is at top of my price range but can us 'old' folks get in and out 20 time a day to take photos? Last choice is a plain jane 3 Series - great price - every one rents them. All of the models listed will (as rental cars) have the smallest possible motors and no option packages. Upgrades to GT's or Coupes almost double the rental costs.  Any words of experience will be much appreciated.