For stairways, I am now convinced this is THE BEST GATE:
http://www.cardinalgates.com/ss30a.html
A professional babyproofer recommended it to us because no matter how we tried, we couldn't get our stairgates to install well. The Cardinal gate is a sturdy (but lightweight) aluminum, not heavy like the other metal gates out there. It has a great simple latch that confounds the kids(and some grandparents), but is easy to work for adults who know how. There's video on the website.
Even though we're onto todder #2, and we had 2 highly-recommended and expensive gates already, we needed help. The main problem for us was that the studs at the top of the stairs did NOT run directly opposite each other, such that if you wanted the gate installed on the studs (which you do) the gate was at a 30-degree angle and didn't close properly. We tried installing at normal angle by using giant anchors. B/c of the weight of the gate, and 2 years of my now-3-year-old pulling on it. We now have giant patches over the giant holes in the walls from where those anchors pulled out. We probably didn't need to replace the gate at the bottom of the stairs, but we liked the ease of use of the Cardinal so much, we got a second.
NO more expensive than other gates. Get this one. It's the best.