Maybe the answer to the OP is a mix of: here are some good spots that do just what you ask for AND let's get SE to make some of these other areas into good party grinds. The first answer helps us today and the second answer helps to create more areas that are party sustainable. Otherwise there are still many areas in the game that are useless for the leveling experience, but with just a few tweaks could be very useful.

Also, does the "dev10xx" tag actually do anything if it is not a real tag?