What do you look for in a Dungeon Set?

Allo, I am working on trying my hand at a Dungeon pack to go along with the other fantasy sets I've done recently.  I'd like to get some feedback from GMs and Players regarding what sort of assets you really look for or wish were more often included in dungeon sets. The set I've designed so far has a range of tiles up to 8x8 in a wide variety of shapes to allow for an appreciable variety of shaped rooms.  While this set primarily supports the typical 2D layout of dungeons, there are some special tiles included (ramps and angled walls) to provide the 3D illusion of additional levels within the same map for GMs wishing to go that route. What I really want to know though is what do GMs most often wish were included in dungeon sets to fulfill their needs that aren't normally covered by just the different variety of rooms?

That ramp effect is snazzy, but seems like it can be easily reproduced by using darker colored tiles- no huge need for specific ramp tiles. Personally, I tend to use a mapping program of some kind instead of laying on tile after tile in roll20; reason being that when I start laying down a lot of tiles on roll20, maps load up really slow and occasionally things bug out.  Sometimes I'll come back to the map and tiles in the back row end up in the front row or vice versa.  Sometimes they change their row order when anyone zooms in. Now, I still do use tiles bought off of roll20, but it's usually so I can get some different flavor to my dungeons and such.  I think if artists were to post tiles that were truly unique, I'd probably consider getting them. I'd love to see a furnishings type of set. Things you might find in a dungeon like altars and torture devices, etc.  You'd have to be unique there too since there's already a wide variety of images that roll20 pulls from.

What sort of mapping software do you use that will create content that is uploadable to and useful with Roll20? I'm new to such things, and would love to be able to create custom maps for my campaigns. Thanks! :)

I use MapTool to create dungeons and maps with tiles since Roll20 doesn't handle that well. You can also paint with textures in MapTool and then export the whole dungeon as a single map to drag and drop into Roll20.

I just bought Dungeonographer and Hexographer after trying the free version for a few weeks. The pro version allows you to export maps to .png files and have plenty of tiles in the starter pack to make pretty good dungeons. There are a few annoyances, don't use free-hand to draw walls and lines. It takes forever to delete a section. But you can adjust the tile size so it is compatible with Roll20's 70 pixels per square. Gimp is also handy to turn white space on a map into transparency. This really cuts down on file size and makes things easier to load. While Gimp can be learned in a few minutes, but takes years to master, Dungeonographer, adn Hexographer are pretty straight forward. They are not based on a CAD format, so non-nerds and non-geeks can make pretty good looking dungeons without having to take a vector graphics class. The biggest hint I can give on these products, is keep thing fairly small. It is better to make a good sized page on Roll20, then use Duneonographer and Hexographer to make small "tiles" than try to make a huge map using the program. Also as far as tokens, and avatars are concerned. I have found having my players using portrait style avatars, and the NPCs and Monsters being top-down tokens makes play go smoother. It is easy to see who is who without using nameplates. Have Fun! 

I use Inkscape and Gimp for designing my dungeon maps, and when I really need some interesting effects, I jump into AutoCAD.