I agree with those asking for more color. Environments are visually unimpressive.
More interesting skies would help also. Look how impressive this sky looks http://i737.photobucket.com/albums/xx12/KAGEHOSHI-/deadspace3iceplanet.png

A swamp and jungle with some in game hazards. Such as quicksand or boulders. I want some maps to be hard to navigate for attackers and defenders. Something with Lots of trees as cover. Not just a regular old tree though. Maybe one lashes out if you get to close and causes some damage to you. Make it kill able though lol.

Maybe some city's off in the distance. Battles take place everywhere so not just in remote area's on deserted planets. Add some highways that have vehicles passing on them before the battle starts and once the mercs start fighting roadblocks are put up that stop vehicles. Have some over passes and intersections. A train track with a train that plows over any merc not looking before they cross.

Some lakes and rivers that are part of the map. I'd really like some rivers that are iced over and hazardous when crossing. Maybe lakes that you can fall through the ice on. Since the dropsuit protects the wearer the game would have to realize there is no escape and offer a quick way out. Such as the suit poisons you so you can respawn.

Corn fields and other farm land for the temperate planets. Maybe a barn on the battlefield that's high tech with moving robotic equipment.

Perhaps on the ocean planets you can have walk ways from part of the facility to the next that are above water and some parts of the facility that are below water. Maybe even a few parts where you can swim under the water from one part of the base to the other to avoid being detected. Kinda like in the movie The Abyss where they launch the underwater rovers. Add some wild life such as a shark or whale that passes by ever so often.

Maybe add an old battlefield map with outdated tanks rusting on the battlefield or an old howitzer that may or may not function anymore :). You'll just have to pull the trigger and find out lol. If it doesn't it blows up in your face haha.

Gas Planets are going to be fun add some gas bubbles that appear randomly and if you fire your weapon ka boom bye bye merc lol. I'm all about environmental hazards if you can't tell already. The gas planet could have walkways and roads that are held in place by giant overhead balloons or solar powered electrical engines that spin rotors. Some walk ways could be enclosed so people don't have to worry about the gases exploding when they fire their weapon.

Perhaps a base located on the side of a volcano. Just have a man made flat area that occasionally gets lava bombs thrown down on it from the volcano. Perhaps have it erupt sometimes and lava block a path for a short time before the base is able to clear it through a vent tunnel system much like a cities water run off system.

Maybe have one located near a residential area mercs have to fight through to get to the base. Nothing fancy just a small town that was unlucky enough to be located between where the mercs base is and the attackers insertion point is. Perhaps the town was founded to support the planetary material collectors placed there. If that is done then I would like to be able to enter a building and snipe from one of the buildings. Maybe have some curtains that help conceal the sniper and every time he shoots the curtain rips making him easier to be spotted so he has to move to another room or run the risk of being spotted and subsequently shot lol.

I hope that gives you some great idea's and I hope some of them are put in. Defiantly add some alien wild life where possible to add the feeling of fighting on different planets. Sure you can't do a whole ecosystem but just some variety and something to look at while we are sprinting to the front lines would be great. Plus I want the other guys destracted by some mermaid while i sneak up behind and unload a clip .

Impact

Setup : Take any planetary map, throw an asteroid at it, then have your cloned lackeys fighting in the bullseye!

Objective : You aren't fighting for the base at this time, you're actually fighting over the useful "shocked" mineral types that will be in the imminent crater.
Mode can be either Ambush, Skirmish, or a "Conquest"-type mode.

EDIT : forgot to mention the base and all assets committed get destroyed at the end, which is expected when a space rock impacts at 10km per second.