Reddit mentions of White Mountains Trail Map: New Hampshire & Maine

This is the White Mountain map I use, along with the AMC White Mountain Guide.
There is also this map of just the Presidential Range.
I don't think any "serious" maps will have interesting information besides trail names and distances. If you want to read thorough descriptions of the trails they I seriously recommend the AMC White Mountain Guide.

https://www.amazon.com/White-Mountains-Trail-Map-Hampshire/dp/1890060232 I would check out this map, this is what my friends and use, it also lists all the 4000 footers if your into that. The presidentials are worth checkin out. The Moriah/Carter ridge is also cool IMO and it looks like you could put together a good loop in the Wild River Wilderness. The cool thing with the whits is there are so many trails you can put together an loop to fit any time frame with a little bit of planning. We always do point to point since we always have 2 cars so nothing specifically comes to mind. Good luck!

I bought this map, and it seems to be quite good (and on waterproof paper too!)

http://www.amazon.com/gp/product/1890060232/ref=oh_details_o06_s00_i00?ie=UTF8&psc=1

There are plenty of options in the white mountains >50 miles. Perhaps not "established routes" in the sense that they don't have names, but the trail system is so robust that there are 100's of options for 50 mile hikes. Get a map like this and just start looking up mountains and campsites and patch something together. https://www.amazon.com/dp/1890060232/ref=cm_sw_r_cp_apa_i_pJROCb3A824Z4

One idea is to find a way to extend the Pemi Loop, either by adding Kinsman's/Cannon/lonesome lake to the west or Crawford Notch/Pierce/Jackson/Webster to the east.

Or you could just follow the Appalachian trail through the Whites from Franconia notch to pinkham notch (or longer).

The Appalachian trail through the mahoosucs (route 2 to the baldpates) is also beautiful.