With all the options we have for viewing query plans I still prefer the graphical view. Combined with tooltips and the occasional journey to the properties dialog it solves the problems I work on. The only downside is that the plan view tends to be verbose and the zoom options just don't work well. Resize to much smaller than the default and you can barely read them, leaving the 'fly over' mode (using the "+" button in the bottom right corner) to navigate the plan looking for whatever is to be found. It's not unworkable, but it does get in the way of a holistic view of what happens when. In other words, we have to divert a portion of our attention from understanding the problem to just using the tools.
Given todays prices there is a simple alternative, just upgrade your primary monitor to 24". No, that won't handle every plan, but it make most of them a lot easier to work with. At probably $400 it's not cheap, but doable. I've seen 22" wide screens recently for under $200.
I do tuning with two monitors, writing/examing queries on the left, Profiler on the right. Alt-Tabbing around is another distraction when I'm problem solving. Using Profiler let's me see easily the exact cost as well as the history of what I've tried/changed so far. I mention that because while using monitors of two different sizes is better than using two monitors, it's also a little visually distracting. The best case is having monitors that are exactly the same.
So there you go fellow DBA's, a starting point for the budget request for next year. Justifying tools is never easy compared to 'solutions', but monitors is an easier sell than some. Struggling to get the monitors approved? Suggest that perhaps your boss, or the CFO/CEO give dual 24" monitors a try to see if there any benefit. Shortly after that monitor sales will go up, everyone in sales will have two monitors, and if you're really lucky, you'll get them too!