I divide them into categories, based on the "rules" to play them (bonuses, attack routes and methods, goals, etc.), though not necessarily strategies. "Complicated" here means complicated rules and structure, not necessarily strategy. Some maps that seem pretty complicated at first are easy once you know them (it just takes time to get there

The "straightforward" maps:
Conquer territories, get 1 army for every 3 territories at the beginning of the round. Gain bonus armies by conquering sections. Many of the "real name" maps fit here. Watch the connections between territories (some are hard to see), learn the bonus values, but no real "tricks"
Classic Shapes
Classic Art
Africa
Alexander's Empire
Ancient Greece
Archipelago
Arctic
Asia
Australia
Benelux
Brazil 2
British Isles 2
Cairns Coral Coast
Cairns Metro
Canada
Caribbean Islands
Charleston
Discworld
Eastern Hemisphere (very large)
Europa
Europe
France
France 1789
Germany
Great Lakes
Haiti
High Seas
Hong Kong
Iberia
Iceland
Indochina
Ireland
Land and Sea
Madagascar
Middle East
Montreal
Netherlands
North America
Philipines
Pugent Sound
Scotland
South America
Soviet Union
USA
World 2.1 (very large)
WWII Australia
Straight, but odd: (play is standard, they jusy look strange)
Crossword
Doodlearth (very small size makes for unusual play .. you can be eliminated before your turn if playing with more than a few.)
Luxembourg Also very small
Chinese Checkers (uniformity makes play go slow at times, especially no card games. Expect multiple player games to take several months)
CCU
Centerscape
Solar System
U.S. Senate
Watch that path!, have some limited attack routes and special bonuses (some auto-deploy), but play about like standard maps:
Berlin 1961
Cairns Metro
Egypt Lower (auto-deployments, unusual connections)
Egypt Upper (auto-deployments, unusual shape)
Greater China
Great Lakes (multiple lake bonuses)
Extreme Global Warming (middle zone has few attack routes)
Italy (city bonuses)
Space
Texan Wars (directional attacks, symbol bonuses)
WWII Eastern Front (one way attack)
WWII Iwo Jima ("tunnels")
"with a little twist": Maps that have minor variations on the "standard"
The Citadel (center goes nuetral at beginning of your next turn)
Dust Bowl (territory losses in "dust" zone, but otherwise not difficult)
Hive VERY large. (Region bonuses are 1 for every 3, but with a maximum of 12. This adds a real change in strategy. Zone bonuses are pretty standard)
Holy Roman Empire (bonuses from groups of cannons in addition to zone bonuses)
Midkemdil – (uses lines instead of areas, has auto-deploy zone)
Rail maps (Rail Europe, Rail US, Rail Australia). Gain the railway for bonuses Rail Australia has some special route bonuses as well.
San Francisco -- watch for Alacatraz
Seige! (unsual shape, nested bonuses)
Tamreil (flag bonuses)
USApocalypse (negative and positive bonuses, careful)
I need a set ...:
Gain your usual 1 army for every 3 territory, but [i]instead of [i]territory bonus, you get a special bonus for conquering specific (unconnected) territories. Bonuses compound with each correct set, so the armies add up very quickly. Some people really like these, others really DON'T. Try them, look over the legend boxes and decide for yourself.
Age of Merchants
Age of Realms 1
Age of Realms 2 Gain resource pairs for bonuses, like in AOR 1, but ice makes connections differ. Also, there is an "objective". if you gain the objective and hold it until your next turn, you can win. More strategy variations than AOR 1
Treasures of the Galapagos
Maps with Bombardments: (other than complicated ones)
Duck and Cover
Feudal War (note: also get 1 army for every 2 castle territory held, auto-deploy on castles)
WWII Western Front (also a capitol bonus, one way attacks)
CHANGE please! A grab bag of maps with varied strategies/features that are different, but not too terribly complicated. Read through the legends (instructions) carefully or look through threads dedicated to these maps for specifics. Some may wish to learn the "basics" (fortifications, cards, etc.) on other maps first. Others may find these may be good places to start if you are willing to read.
American Civil War (remote attacks and bombardments, also "capitol" bonuses)
Arms Race! (different concept-- get missile to win)
Poker Club (Bonuses based on Poker hands)
Circus Maximus No special territory or bonuses (just the 1 for every 3 armies), one-direction attacks and a very odd shape make for truly different play.
City Mogul (lots of armies, different bonus structure, bombardments)
Conquer 4 (get 4 in a row to gain bonuses)
Draknor Level 1(warning! filled with one-way attack routes that make this a difficult map, though bonuses, etc. are not complicated)
Europe 1914 (objective)
Holy Roman Empire (special bonuses)
Halloween Hallows (unusual attacks, bonuses)
Imperium Romanum (watch the special bonuses, also legend is unusual to read)
King of the Mountains (unusual look, one-way remote attacks, etc.)
Madness (a few different attack routes and bonuses)
Malta (remote attacks, special bonuses)
New World(start from a base, remote attacks, auto-deploy and special bonus structure)
NYC (various attack routes, multiple island bonuses)
Oasis (penalties, for desert territories, bonus for small Oasis, Objective)
Syndey Metro – special attack routes
8 Thoughts bonus for sections and for symbols, penalty, odd shape
Just Plain Complicated: These have multiple, complicated bonuses, varied attack routes (one ways, bombardments, etc.), various "sneaky" attributes and are generally larger than the other maps. Suggest learning the basics of CC (fortifications, spoils, rough strategies) before tackling these, but they can certainly be fun.
Age of Realms 3 (has resource pairs, NO regular territory bonus -- you get just 3 no matter how many territories you own, attacks and bonuses that vary with regions... play is quite differant from ANY other map)
Bamboo Jack
Battle for Iraq
Battle of Actium
Conquerman
D-Day Omaha Beach
Das Schloss
Egypt Valley of the Kings
Forbidden City
Operation Drug War
Pearl Harbor
Prohibition Chicago
Supermax: Prison Riote
Waterloo
WWII Ardennes
WWII Gazales
The Case of the Missing Maps:
The following maps have been closed.
Saint Patrick's Day Was a non-standard holiday map. Unlike Halloween Hallows (which was originally introduced as a holiday map), this one was deemed not suitable for permanent inclusion in CC maps, but it may be opened in future years.
OTHERS
There are a couple of other maps that you might occasionally see mentioned (mostly if you go back a ways in threads). They were removed for copyright or other reasons and cannot be brought back, though in most cases a close variant is active now (one with the same basic bonuses and attack routes, though the looks, names and design will be quite different).
Descriptive terms:
Legend-- as in "map legend" these are the explanations for symbols, bonuses, etc.
Bombardment-- you can attack remotely, but the last territory goes neutral. You never take it over (usually you can capture the territories directly also).
Auto-deploy extra armies added automatically to that space if you own it at the beginning of your territories.
Objective: Some maps offer an alternative way to win. If you capture the objective and hold it, you win. Currently, all maps except Das Schloss (not available until its reworked) can be won the usual way (capture all your enemy) as well.
Remote attack: Attack a non-adjacent country and conquer it. (you are allowed to move territories there)
Beta by a map in "game finder" or "Start game" menus just means its a new map. Maps are tested, but sometimes new problems are found once lots of people are playing. Usually, its something very small (changing the wording on a legend, etc.), but once in a while its a real problem (as with Das Schloss). This distinguishes the new maps, that might be changed, from those that are fully set. They are often excellent maps for beginners since no one knows them well yet, but do look them over before beginning a game... and yes, they might occasionally change during a game.