I used mapmyrun.com to figure out the basic walking routes we take from various hotels.
From the front of the Tropicana across Harbor it's .22 mile, but that isn't completely accurate as I just noticed I didn't go exactly to the center of the Esplanade (so add maybe .1 onto it). Just updated it, and moving my marker from where it was to the center start thing in the Esplanade makes it .29 mile.
From DLH (at the hat, not even counting if you're in the far tower) through DTD to the center of the Esplanade, it's .47 mile. Nope, just updated using more perfect markers, and it's .43 mile.
From the front of PPH using the GCH path, it's .45 mile.
PPH through DTD to the center start of the Esplanade, following PPH's signs, using markers to the best of my ability (considering the satellites don't show *inside* the buildings and I'm not totally sure where the exits are), starting at approximately the area of the elevators.... .63 mile.
PPH to the monorail following PPH's signs: .29 mile.
PPH to the monorail going through the Grand and back "up" DTD: .41 mile
DLH to the monorail: 0.9 mile
GCH to the monorail (starting at the point where you start the walk to get to the DTD exit, where you'd start the inner Grand portion of the PPH's shortcut): .22 mile
Re: the monorail, we did that a couple times on our first PPH stay, but every time the monorail was CLOSED, so it was absolutely useless. We followed the PPH signs, so that takes you back behind DTD and walking past DLH, then turning into DTD past ESPN zone and Rainforest Cafe to get to the station...
Using the monorail gets you into Tomorrowland, so if you really want to visit Main Street, or certain other areas of the park, it might not make sense to use the monorail to save steps. Now if you're heading to TL, or further in (ToonTown, IASW), it can make sense.