(Apologies for the maker of that Antlion Surival map with the "fake" dropship. No offence for you, it's nice but just short )
My idea of a good antlion surival map would be;
-The general base where you are be fairly big, enough so you could spam 20 jeeps side by side. in all directions but up and down.
-The antlions spawning not be in open plain sight, this is rather boring for people as you'll just grab a gun that shoots powerful enough and spawn camp them. Making it very boring, and thus should be in small caves that have trigger_hurts 99999 on players so you can't attempt spawn camping.
-The initial escape plan be more advanced, like; move from there to here, and from here to over there and you will be rescued. Sounds a bit plain, cause of common sense: "Why don't they just come to us?", again, common sense: Maybe it's a ground vehicle? We don't want Guards running into them. So nicely done bases would be good. Constantly failing shields and re-buildable walls would be good (picking up a wall and placing it where it should be)
-Detailed bases. You may think "Why does it need to be detailed?". Well, basically, the map looks uninteresting, and without detail, maps get boring, and gameplay does too. So spice up your entity creating a bit, create more buildings that have ammo stocks in them!
-Those pesky merchants! When you spawn, you should spawn in a vote room, and you should walk into two areas: One that if has most players on that side will win that option: Merchants or No merchants. If No merchants, then in it's spot will just be a shelf with weapons, but only limited to Sniper Rifle, Pistol, Shotgun, AR2, Grenades, and SMG's. RPG's for the Antlion Guards, I must remember.
-Those antlions spawn one at a time. Why not make three spawns for them, but make it every so often? Such as; after 5 minutes of constant antlion attack, players have 1 minute of break, and 1 minute after that of antlion harrassment. After that one minute, one or two guards come out. This way we don't get badly overwhelmed when it's just a few players, since we can get our shit together, make sure we have stuff ready, and then attack again.
-Whose stealin' mah health?! Those damn machines don't give me much armour or health! Well why not just make it so it heals 99999, and if it happens to run out (wtf?) then it should reset in .1 seconds. Same for the armour.
-Oh noes my base is dying!111s! I must buy more! There should be 5 turret spawners: You can only have 5 or 6 on the field at once. It takes a normal antlion 25 hits to kill (each hit counts for an antlion, so you're screwed if theres more than 1 hitting that turret), it takes a Worker 10 acid hits (if they do that, if not, 20), and antlion guards 2 hits.
-I can't snipe, wtf? What we need are sniper towers, and generally a bunker in the middle. Like the current Antlion Survival map, there's a useless bunker with no machine gun on the left side of the map, and a good sniping spot for which the antlions can also ambush you (has happened about 37 times so far. Epic spot when you get raped by those antlions)
-Hey wheres the objectivez? We need thumpers, ones that will take damage and automatically shut off for at least 2:30 minutes before they need re-activating. A small timer should appear above the button part. Around the thumper should be a couple of barricades that stop antlions just jumping in nilly willy. This way, it adds an interesting object, because it's like "Defend the Hill", and the Antlions are attacking it. On a server of 16 people, you could send 3 people to defend the thumper which should eventually start damaging Antlions by 2 HP every 10 seconds (Balancing), next to every thumper should be a grenade stock, pistol stock, and an ar2 stock. No SMG stock for a reason of SMG's for some reason being one of the most powerful weapons next to the RPG and AR2 (AR2 is rare anyway).
-Thumpers are losing power! Well to resolve this you're gonna need a power supply. Head over to that antlion infested place over there far from the base, pick up a power generator (car battery or the engine itself) and place it where the thumper needs it. Each supply should last 8 whole minutes before it needs replacing. It should turn red to indicate this.
I'll add more as I think of 'em.
The Responser's Conclusion
-Spawn camping, people will always do it, but we can do it EP1 style, make antlions jump over the hills and such as well as spawning from the sand, the random per of antlions should drop in every 10 seconds. Three should visit. One of those antlions must be a worker.
-Instead of using caves we can use the sand spawning system as the first response suggests, but it will need to have some kind of moving spawner, so they just don't spawn in one spot.
Quickie picture of suggested map design:
Note: I said quickie. I'm not good with MS paint either. So shutup.
By the way, that's not exactly a full-size map, it's a fairly big, but that's because of the player's vehicle.
Oh, and the vehicle that the players use is abandoned at the bridge because it won't fit through the breakable cave will it?
Escape vehicle is a truck, not a dropship, it's armoured and will shoot antlions on it's way so you know how it got there without being damaged logically.
The Good Responder's Suggestions
And btw. I don't really like those defence only maps, though antlion_attack is a great one. I'd really appreciate it if you had to get to another base or something. Maybe there could be a map series in which you first have to escape and later on decide to just wipe out the nest by placing a WTF-bomb in the cave with the comb things. Well, you guys know what I mean, haha...