My suggestion on map guidelines is to pretty much ignore the number of provinces. The real factor on how the game plays out is how many provinces are between the players capitals. So Provinces per player is far more important than how big the map is in total. Some "small" maps can be huge with few players and even the maximum map (1500 provinces) is only a medium to large game if you fill all the nation slots. The game itself (n the Dom3 settings) defines Small/Medium/Large maps as being 10/15/20 provinces per player so a very different game would be anything less than 10 or more than 20 each.
Having NI or PI maps is best created. Choose a map and then run it thru a script to turn it into an NI or PI version. I have a PI map on my site if you want to play test one.
http://forum.shrapnelgames.com/showthread.php?t=46306
Tower maps can limit battlefronts. But in general I consider them best for newbie games to insure that everyone only has 2 enemy neighbors for most of the game.
If you look at the maps I generate daily, they tend to provide large areas with lots of chokepoints. Mostly preferred by Solo players but do tend to get a good amount of use in MP games also.
http://www.dom3minions.com/RandomizedMaps.htm
If you dont like any of those, they recreate each day. I also have a "keepers" directory of ones I liked and set aside. Or its easy to edit a script for whatever settings and color preferences you like to generate you a catalog of possibles. It usually takes about 2 hours to run one.
There are maps done by other people who have specifically created styles that limit battlefronts. Such as everyone starting in fairly separated areas that meet in the middle of the map. But those are mostly for competition style games of 6-8 players.