The idea of having a lander type craft delivering supplies is interesting, but in a way not practical.
The main factor being fuel. Unless it could be locally produced in sufficient quantities, fuel would need to be shipped from Earth. Not to mention needing to actually ship such a craft to, or construct and assemble it on, Mars. Anything shipped from Earth makes things time consuming and very expensive.
That makes rovers more practical and sensible just for delivering supplies earlier on.
The subject of landers and such is touched upon in another topic (I forget which one, but I think one started by Hyper).
If a lander does show up, it is either a one way trip (free spare parts/equipment/shelter?), or a dual stage craft with an ascent stage that is not going anywhere until they have whatever people or materials are going to be taken to orbit to an awaiting interplanetary transfer craft. (With a caravan arriving sooner or later with said people/stuff to be shipped to Earth?)
Also consider that it takes a good bit of time to prepare and launch even a single space mission, and the fact it takes a half year to get to Mars. That means seeing rocket contrails and rocket engine propelled flying craft are going to be extremely rare early on, not to mention the whole 'needle in a haystack' effect of such a lander/rocket passing nearby the player's position in the first place, so should be a rare event/sighting at best.
Now, if the Mars Constellation mission concept or the SKYLON based TROY Mars Mission concept were to become a reality, then it could be a more viable option to have (likely single use) landers used to deliver supplies/materials from an orbiting interplanetary transfer craft.
The cargo lander from the Mars Constellation could likely deliver supplies/materials for an entire base all by itself.
For me, it would nice to start a phase looking at one or more rovers as they pull away with the work team that had assembled structures and installed heavy equipment between phases, with several empty rover beds (and any 'extra' rovers at the base/outpost) give a better feel of 'where' those supplies came from. Perhaps toss in getting some sort of 'good luck' message from the work team as they leave (be it audio or just text in the message window). Toss in a larger 'caravan' type rover (or towed 'self propelled' trailers) that gives the impression it can carry a lot of people and supplies.
Even that has its own obstacles though. I don't think there is any sort of real AI in MC:C at present, so anything that moves on its own would be likely limited to being 'on rails', or otherwise controlled by a limited/restrict script of some sort.
I would agree it would be interesting to have equipment get different sounds based on their condition.
And warning klaxons/lights to help add to the impact when you get a message that something bad just happened, such as the filter in the air scrubber catching on fire... of which I had happen before. In hindsight, lack of clouds of smoke, flashing warning lights and warning klaxons made the event a little anti-climactic.
By 'players', do you mean actual players? Or do you mean just computer controlled characters? (as in NPCs, a.k.a. Non-Player Characters).
One of the other topics (I think one started by Hyper) already had people bring up the subject of finding assorted things, such as old probes and such, and of other things be added to improve immersion, such as random radio chatter and such.
I see there is a fellow KSP fan around. Imagine the issues with getting even a small automated rover to Duna if you had an astronomical bill (pun intended) tacked onto things. That is a factor to consider here. MC:C tries to stick to realism, scientific fact, etc. "Sounds cool" quickly clashes with "Where do we get the money for that?"