There was a great thread back in the old forums for this topic, it was started by Spliff Craven if I remember correctly.
Here are some of the suggestions that I can remember.
Dock yard by the ocean with large cranes and containers.
Space Port with hangers and ships.
Bombed out city in ruins. See below
Extinct volcanic map with lava tubes and other weird landscape stuff.
Floating air base that you can fall off of it you are not careful. see below.
Vitrolium processing plant like a large factory with an eerie blue glow, See below.
Large refinery type map, See below.
Night time maps, was a popular suggestion.
I'll add more when I an remember them.
I want a Team Capture the flag in a space port.
I had a thread on the old forum with some ideas and description.
The Lore would be based around the need for battleships in siege mode. Basically two teams trying to capture control of an abandoned space shipyard with a mostly built battleship as the centrepiece. They are powered by massive 2-part power cores which are manufactured on opposite sides of a shipyard due to volatile nature. Due to this the manufacturing plant will only release one core at a time (if it no longer detects one in the base it releases another).
Traditional CTF:
You have to get a core from the other teams side and take it back to your side. Cannot install if the other team holds your half so you need to kill their flag-bearer and touch your core to cause it to self destruct. You can then return the enemy core alongside a newly released part. Install 3 cores to win and activate base defences. Then the entire other team gets insta-gibbed by the base defences.
Hybrid with a king of the hill aspect:
You have to get a core from the other teams side and take it to combine with your own half and install both in a receiver in the ship to power its defences and defend for a short period while the defences come online. Then the entire other team gets insta-gibbed by the ships defences.
I'd like something with ship with multilevel interior, a port/shipyard with gantries either side, and also ability to get above and below the ship with bounce pads to give even more vertical play than origin.

^ Image of a generic space shipyard for reference, Hawken one should attempt to look like the battleships in siege with more gantries down each side and ways to play above and below the ship.
EDIT: should easily be able to work in ability to have Siege and MA game modes on the same map.
Cheers,
6ixxer
Edited by 6ixxer, 10 February 2016 - 07:25 PM.