As a lifelong denizen of the East Coast, an old school field geologist by early 1970s training, a map study junkie who 8 years sought to plot out all of the Appalachian Trail road crossings from Georgia to Maine, and a guy who owns no GPS or map software outside of what came in my iPhone, I offer the following regarding DeLorme and East Coast field work planning:
1) Mark is spot-on with his opinion that Benchmarks are superior to DeLormes for states which are covered by both, which are primarily from the Pacific east to the Rockies. I completely concur.
2) Mark is also spot-on with his opinion that in the East, and I'll here add the Midwest, the DeLormes are better than nothing. Completely concur.
And I'll add this: Generally following the Appalachian Mountains, from North Georgia through parts of TN, NC, WV, and VA, the National Geographic "Trails Illustrated" folding, water resistant maps (TIs) offer utility for field use vastly superior to Benchmarks and DeLormes. Part of the exceptional utility is due to scale--generally finer than an inch to a mile vs Benchmark/DeLorme generally being an inch to 4 miles. The topographic contour interval is appropriate and at field use utility, generally at 40' contour intervals. The TIs normally show NF boundaries clearly, NF numbered roads and trails, NF gates along roads and trails (VERY useful since NF gates are normally closed/opened on seasonal schedules). I have not bothered to check on howmuch of the Mid-Atlantic or the Northeast parts of the Appalachians are now covered by TIs, but at the least I would expect and hope that the Greens in VT, the Whites in NH, and most of central Maine would be covered--all three areas being generally along the AT corridor.
Outside of the Appalachians, the standard DeLormes are, to my knowledge, the only game in town. My primary beef with the DeLormes for the Southern states is the contour interval is nearly useless (often 100' or 30 to 50 meters) in areas having barely that degree of topographic relief) and are printed in very faint ink. Little of an area's topography really "pops" out at you. A close second in complaints is the excessive number and print font size of cultural features, principally towns and similar place names. Such obscures stream drainage patterns which should be the go-to in the absence of decent topographic contour expression.
All of that said, I do not venture afield in any state not covered by Benchmark without a DeLorme in the truck.
Foy