I had available to me the Harrison map and also GPS-enabled topo loaded on my iPhone. However, we didn't really use them for the USL/Langley portion (though they were helpful for the LSL/Miter Basin/Skyblue Lake/USL portion).
By the time of our our true summit day, we'd already spent some time in the region and had a sense of how it all fit together. We had came in from Cottonwood Lakes basin, and traversed the plateau from NAP to Langley at the start of the trip, when we first attempted the Langley summit. So I was able to scope out the general geography -- where the passes were in relation to Langley, etc. -- during that first (aborted) attempt. Then, later in the trip, when we got to USL after exploring The Miter, I spent a couple of hours locating and scoping out the use trail up to Langley the day before we did the actual summit attempt.
By the way, I'm with Glenn...Miter Basin/Skyblue Lake deserves a full day. It's not all that long or hard (though you can extend it for more challenge), but it's not something to rush.
